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msm_serial fixes and improvements

PATCH In review Stephen Boyd 4 participants 13 messages Jul 24, 2013 – Jul 29, 2013

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Stephen Boyd

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#0 lore raw

cover msm_serial fixes and improvements

Here are a couple fixes and improvements to the msm_serial driver. The first two patches fix a bug on UARTDM devices and silence sparse warnings. The last two patches improve the baud code detection and increase the throughput on UARTDM devices.

After this it is rather trivial to add support for newer UARTDM devices via new compatible fields.

Stephen Boyd (4):
msm_serial: Fix NUL byte output on UARTDM
msm_serial: Fix sparse warnings
msm_serial: Make baud_code detection more dynamic
msm_serial: Send more than 1 character at a time on UARTDM

 drivers/tty/serial/msm_serial.c | 180 ++++++++++++++++++++--------------------
 drivers/tty/serial/msm_serial.h |  19 ++---
 2 files changed, 97 insertions(+), 102 deletions(-)
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#1 lore raw

PATCH 1/4 msm_serial: Fix NUL byte output on UARTDM

UARTDM serial devices require us to wait for the entire TX fifo to drain before we can change the contents of the NCF_TX register. Furthermore, if we write any characters to the TX fifo within the same clock cycle of changing the NCF_TX register the NCF_TX register won't latch properly.

To fix these issues we should read back the NCF_TX register to delay any TX fifo accesses by a clock cycle and we should wait for the TX fifo to drain (instead of just waiting for the fifo to be ready to receive more characters). Failure to do so leads to random NUL bytes interspersed in the output.

Signed-off-by Stephen Boyd <[email protected]>
---
 drivers/tty/serial/msm_serial.c | 14 +++++++++-----
 drivers/tty/serial/msm_serial.h |  1 +
 2 files changed, 10 insertions(+), 5 deletions(-)
drivers/tty/serial/msm_serial.c +9 -5
index 2c6cfb3..fa3fc67 100644
@@ -50,11 +50,14 @@ struct msm_port {
 	unsigned int		old_snap_state;
 };
 
-static inline void wait_for_xmitr(struct uart_port *port, int bits)
+static inline void wait_for_xmitr(struct uart_port *port)
 {
-	if (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY))
-		while ((msm_read(port, UART_ISR) & bits) != bits)
-			cpu_relax();
+	while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {
+		if (msm_read(port, UART_ISR) & UART_ISR_TX_READY)
+			break;
+		udelay(1);
+	}
+	msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR);
 }
 
 static void msm_stop_tx(struct uart_port *port)

@@ -194,8 +197,9 @@ static void handle_rx(struct uart_port *port)
 
 static void reset_dm_count(struct uart_port *port)
 {
-	wait_for_xmitr(port, UART_ISR_TX_READY);
+	wait_for_xmitr(port);
 	msm_write(port, 1, UARTDM_NCF_TX);
+	msm_read(port, UARTDM_NCF_TX);
 }
 
 static void handle_tx(struct uart_port *port)
drivers/tty/serial/msm_serial.h +1 -0
index e4acef5..15c186e 100644
@@ -71,6 +71,7 @@
 #define UART_CR_CMD_RESET_RFR		(14 << 4)
 #define UART_CR_CMD_PROTECTION_EN	(16 << 4)
 #define UART_CR_CMD_STALE_EVENT_ENABLE	(80 << 4)
+#define UART_CR_CMD_RESET_TX_READY	(3 << 8)
 #define UART_CR_TX_DISABLE		(1 << 3)
 #define UART_CR_TX_ENABLE		(1 << 2)
 #define UART_CR_RX_DISABLE		(1 << 1)
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hosted by The Linux Foundation
Acked-by on v1 1/4
#2 lore raw

Re: [PATCH 1/4] msm_serial: Fix NUL byte output on UARTDM

Quoted 12 lines · Stephen Boyd

UARTDM serial devices require us to wait for the entire TX fifo to drain before we can change the contents of the NCF_TX register. Furthermore, if we write any characters to the TX fifo within the same clock cycle of changing the NCF_TX register the NCF_TX register won't latch properly.

To fix these issues we should read back the NCF_TX register to delay any TX fifo accesses by a clock cycle and we should wait for the TX fifo to drain (instead of just waiting for the fifo to be ready to receive more characters). Failure to do so leads to random NUL bytes interspersed in the output.

Quoted 5 lines
Signed-off-by Stephen Boyd <[email protected]>

---
drivers/tty/serial/msm_serial.c | 14 +++++++++----- drivers/tty/serial/msm_serial.h | 1 +

2 files changed, 10 insertions(+), 5 deletions(-)
Acked-by David Brown <[email protected]>
Signature · 3 lines
sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation
author
#3 lore raw

PATCH 2/4 msm_serial: Fix sparse warnings

In reply to Stephen Boyd

drivers/tty/serial/msm_serial.c:302:6: warning: symbol 'msm_set_mctrl' was not declared. Should it be static? drivers/tty/serial/msm_serial.c:597:17: warning: incorrect type in argument 2 (different address spaces)
drivers/tty/serial/msm_serial.c:597:17: expected void volatile [noderef] <asn:2>*addr drivers/tty/serial/msm_serial.c:597:17: got unsigned int * drivers/tty/serial/msm_serial.c:608:33: warning: incorrect type in argument 1 (different address spaces)
drivers/tty/serial/msm_serial.c:608:33: expected void volatile [noderef] <asn:2>*addr drivers/tty/serial/msm_serial.c:608:33: got unsigned int *gsbi_base drivers/tty/serial/msm_serial.c:648:37: warning: incorrect type in assignment (different address spaces)
drivers/tty/serial/msm_serial.c:648:37: expected unsigned int *gsbi_base drivers/tty/serial/msm_serial.c:648:37: got void [noderef] <asn:2>*

Mark the ioremapped memory as __iomem and use writel instead of iowrite because we're not dealing with PCI devices. Also, mark msm_set_mctrl() static because it isn't used outside this file.

Signed-off-by Stephen Boyd <[email protected]>
---
 drivers/tty/serial/msm_serial.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)
drivers/tty/serial/msm_serial.c +7 -10
index fa3fc67..cab4105 100644
@@ -45,7 +45,7 @@ struct msm_port {
 	struct clk		*clk;
 	struct clk		*pclk;
 	unsigned int		imr;
-	unsigned int            *gsbi_base;
+	void __iomem		*gsbi_base;
 	int			is_uartdm;
 	unsigned int		old_snap_state;
 };

@@ -299,7 +299,7 @@ static void msm_reset(struct uart_port *port)
 	msm_write(port, UART_CR_CMD_SET_RFR, UART_CR);
 }
 
-void msm_set_mctrl(struct uart_port *port, unsigned int mctrl)
+static void msm_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 	unsigned int mr;
 	mr = msm_read(port, UART_MR1);

@@ -593,12 +593,10 @@ static void msm_release_port(struct uart_port *port)
 	port->membase = NULL;
 
 	if (msm_port->gsbi_base) {
-		iowrite32(GSBI_PROTOCOL_IDLE, msm_port->gsbi_base +
-			  GSBI_CONTROL);
-
-		gsbi_resource = platform_get_resource(pdev,
-							IORESOURCE_MEM, 1);
+		writel_relaxed(GSBI_PROTOCOL_IDLE,
+				msm_port->gsbi_base + GSBI_CONTROL);
 
+		gsbi_resource = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 		if (unlikely(!gsbi_resource))
 			return;
 

@@ -670,10 +668,9 @@ static void msm_config_port(struct uart_port *port, int flags)
 		if (ret)
 			return;
 	}
-
 	if (msm_port->is_uartdm)
-		iowrite32(GSBI_PROTOCOL_UART, msm_port->gsbi_base +
-			  GSBI_CONTROL);
+		writel_relaxed(GSBI_PROTOCOL_UART,
+				msm_port->gsbi_base + GSBI_CONTROL);
 }
 
 static int msm_verify_port(struct uart_port *port, struct serial_struct *ser)
Signature · 2 lines
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hosted by The Linux Foundation
Acked-by on v1 2/4
#4 lore raw

Re: [PATCH 2/4] msm_serial: Fix sparse warnings

Quoted 15 lines · Stephen Boyd

drivers/tty/serial/msm_serial.c:302:6: warning: symbol 'msm_set_mctrl' was not declared. Should it be static? drivers/tty/serial/msm_serial.c:597:17: warning: incorrect type in argument 2 (different address spaces)
drivers/tty/serial/msm_serial.c:597:17: expected void volatile [noderef] <asn:2>*addr drivers/tty/serial/msm_serial.c:597:17: got unsigned int * drivers/tty/serial/msm_serial.c:608:33: warning: incorrect type in argument 1 (different address spaces)
drivers/tty/serial/msm_serial.c:608:33: expected void volatile [noderef] <asn:2>*addr drivers/tty/serial/msm_serial.c:608:33: got unsigned int *gsbi_base drivers/tty/serial/msm_serial.c:648:37: warning: incorrect type in assignment (different address spaces)
drivers/tty/serial/msm_serial.c:648:37: expected unsigned int *gsbi_base drivers/tty/serial/msm_serial.c:648:37: got void [noderef] <asn:2>*

Quoted 8 lines

Mark the ioremapped memory as __iomem and use writel instead of iowrite because we're not dealing with PCI devices. Also, mark msm_set_mctrl() static because it isn't used outside this file.

Signed-off-by Stephen Boyd <[email protected]>

---
drivers/tty/serial/msm_serial.c | 17 +++++++----------

1 file changed, 7 insertions(+), 10 deletions(-)
Acked-by David Brown <[email protected]>
Signature · 3 lines
sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation
author
#5 lore raw

PATCH 3/4 msm_serial: Make baud_code detection more dynamic

In reply to Stephen Boyd

Currently msm_set_baud_rate() assumes the uart clock rate is 1.8432 MHz. This is not always true, and limits our options to program the baud rate. Instead of assuming the rate and hard-coding the baud_code based on it, calculate the divider that we want and try to find the closest baud_code that matches. This allows us to support uarts with faster clock speeds.

Signed-off-by Stephen Boyd <[email protected]>
---
 drivers/tty/serial/msm_serial.c | 98 ++++++++++++++++++-----------------------
 drivers/tty/serial/msm_serial.h | 18 ++------
 2 files changed, 48 insertions(+), 68 deletions(-)
drivers/tty/serial/msm_serial.c +44 -54
index cab4105..cef8f40 100644
@@ -322,70 +322,60 @@ static void msm_break_ctl(struct uart_port *port, int break_ctl)
 		msm_write(port, UART_CR_CMD_STOP_BREAK, UART_CR);
 }
 
+struct msm_baud_map {
+	u16	divisor;
+	u8	code;
+	u8	rxstale;
+};
+
+static const struct msm_baud_map *
+msm_find_best_baud(struct uart_port *port, unsigned int baud)
+{
+	unsigned int i, divisor;
+	const struct msm_baud_map *entry;
+	static const struct msm_baud_map table[] = {
+		{ 1536, 0x00,  1 },
+		{  768, 0x11,  1 },
+		{  384, 0x22,  1 },
+		{  192, 0x33,  1 },
+		{   96, 0x44,  1 },
+		{   48, 0x55,  1 },
+		{   32, 0x66,  1 },
+		{   24, 0x77,  1 },
+		{   16, 0x88,  1 },
+		{   12, 0x99,  6 },
+		{    8, 0xaa,  6 },
+		{    6, 0xbb,  6 },
+		{    4, 0xcc,  6 },
+		{    3, 0xdd,  8 },
+		{    2, 0xee, 16 },
+		{    1, 0xff, 31 },
+	};
+
+	divisor = uart_get_divisor(port, baud);
+
+	for (i = 0, entry = table; i < ARRAY_SIZE(table); i++, entry++)
+		if (entry->divisor <= divisor)
+			break;
+
+	return entry; /* Default to smallest divider */
+}
+
 static int msm_set_baud_rate(struct uart_port *port, unsigned int baud)
 {
-	unsigned int baud_code, rxstale, watermark;
+	unsigned int rxstale, watermark;
 	struct msm_port *msm_port = UART_TO_MSM(port);
+	const struct msm_baud_map *entry;
 
-	switch (baud) {
-	case 300:
-		baud_code = UART_CSR_300;
-		rxstale = 1;
-		break;
-	case 600:
-		baud_code = UART_CSR_600;
-		rxstale = 1;
-		break;
-	case 1200:
-		baud_code = UART_CSR_1200;
-		rxstale = 1;
-		break;
-	case 2400:
-		baud_code = UART_CSR_2400;
-		rxstale = 1;
-		break;
-	case 4800:
-		baud_code = UART_CSR_4800;
-		rxstale = 1;
-		break;
-	case 9600:
-		baud_code = UART_CSR_9600;
-		rxstale = 2;
-		break;
-	case 14400:
-		baud_code = UART_CSR_14400;
-		rxstale = 3;
-		break;
-	case 19200:
-		baud_code = UART_CSR_19200;
-		rxstale = 4;
-		break;
-	case 28800:
-		baud_code = UART_CSR_28800;
-		rxstale = 6;
-		break;
-	case 38400:
-		baud_code = UART_CSR_38400;
-		rxstale = 8;
-		break;
-	case 57600:
-		baud_code = UART_CSR_57600;
-		rxstale = 16;
-		break;
-	case 115200:
-	default:
-		baud_code = UART_CSR_115200;
-		baud = 115200;
-		rxstale = 31;
-		break;
-	}
+	entry = msm_find_best_baud(port, baud);
 
 	if (msm_port->is_uartdm)
 		msm_write(port, UART_CR_CMD_RESET_RX, UART_CR);
 
-	msm_write(port, baud_code, UART_CSR);
+	msm_write(port, entry->code, UART_CSR);
 
 	/* RX stale watermark */
+	rxstale = entry->rxstale;
 	watermark = UART_IPR_STALE_LSB & rxstale;
 	watermark |= UART_IPR_RXSTALE_LAST;
 	watermark |= UART_IPR_STALE_TIMEOUT_MSB & (rxstale << 2);
drivers/tty/serial/msm_serial.h +4 -14
index 15c186e..469fda5 100644
@@ -38,19 +38,7 @@
 #define UART_MR2_PARITY_MODE_SPACE	0x3
 #define UART_MR2_PARITY_MODE		0x3
 
-#define UART_CSR	0x0008
-#define UART_CSR_115200	0xFF
-#define UART_CSR_57600	0xEE
-#define UART_CSR_38400	0xDD
-#define UART_CSR_28800	0xCC
-#define UART_CSR_19200	0xBB
-#define UART_CSR_14400	0xAA
-#define UART_CSR_9600	0x99
-#define UART_CSR_4800	0x77
-#define UART_CSR_2400	0x55
-#define UART_CSR_1200	0x44
-#define UART_CSR_600	0x33
-#define UART_CSR_300	0x22
+#define UART_CSR			0x0008
 
 #define UART_TF		0x000C
 #define UARTDM_TF	0x0070

@@ -152,6 +140,7 @@ static inline void msm_serial_set_mnd_regs_tcxo(struct uart_port *port)
 	msm_write(port, 0xF1, UART_NREG);
 	msm_write(port, 0x0F, UART_DREG);
 	msm_write(port, 0x1A, UART_MNDREG);
+	port->uartclk = 1843200;
 }
 
 /*

@@ -163,6 +152,7 @@ static inline void msm_serial_set_mnd_regs_tcxoby4(struct uart_port *port)
 	msm_write(port, 0xF6, UART_NREG);
 	msm_write(port, 0x0F, UART_DREG);
 	msm_write(port, 0x0A, UART_MNDREG);
+	port->uartclk = 1843200;
 }
 
 static inline

@@ -170,7 +160,7 @@ void msm_serial_set_mnd_regs_from_uartclk(struct uart_port *port)
 {
 	if (port->uartclk == 19200000)
 		msm_serial_set_mnd_regs_tcxo(port);
-	else
+	else if (port->uartclk == 4800000)
 		msm_serial_set_mnd_regs_tcxoby4(port);
 }
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation
Acked-by on v1 3/4
#6 lore raw

Re: [PATCH 3/4] msm_serial: Make baud_code detection more dynamic

Quoted 7 lines · Stephen Boyd

Currently msm_set_baud_rate() assumes the uart clock rate is 1.8432 MHz. This is not always true, and limits our options to program the baud rate. Instead of assuming the rate and hard-coding the baud_code based on it, calculate the divider that we want and try to find the closest baud_code that matches. This allows us to support uarts with faster clock speeds.

Quoted 5 lines
Signed-off-by Stephen Boyd <[email protected]>

---
drivers/tty/serial/msm_serial.c | 98 ++++++++++++++++++----------------------- drivers/tty/serial/msm_serial.h | 18 ++------

2 files changed, 48 insertions(+), 68 deletions(-)
Acked-by David Brown <[email protected]>
Signature · 3 lines
sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation
#7 lore raw

Re: [PATCH 3/4] msm_serial: Make baud_code detection more dynamic

In reply to Stephen Boyd
Quoted 19 lines · Stephen Boyd

[snip]

drivers/tty/serial/msm_serial.c +18 -0
+       unsigned int i, divisor;
+       const struct msm_baud_map *entry;
+       static const struct msm_baud_map table[] = {
+               { 1536, 0x00,  1 },
+               {  768, 0x11,  1 },
+               {  384, 0x22,  1 },
+               {  192, 0x33,  1 },
+               {   96, 0x44,  1 },
+               {   48, 0x55,  1 },
+               {   32, 0x66,  1 },
+               {   24, 0x77,  1 },
+               {   16, 0x88,  1 },
+               {   12, 0x99,  6 },
+               {    8, 0xaa,  6 },
+               {    6, 0xbb,  6 },
+               {    4, 0xcc,  6 },
+               {    3, 0xdd,  8 },
+               {    2, 0xee, 16 },

drivers/tty/serial/msm_serial.c static void msm_break_ctl(struct uart_port *port, int break_ctl) · line 361

Quoted 10 lines
drivers/tty/serial/msm_serial.c +10 -0
+               {    1, 0xff, 31 },
+       };
+
+       divisor = uart_get_divisor(port, baud);
+
+       for (i = 0, entry = table; i < ARRAY_SIZE(table); i++, entry++)
+               if (entry->divisor <= divisor)
+                       break;
+
+       return entry; /* Default to smallest divider */

Shouldn't matter, but you're not defaulting to the smallest divider. Your are defaulting to an undefined value, as entry will be off the array once i == ARRAY_SIZE().

Regards,
Bjorn

author
#8 lore raw

Re: [PATCH 3/4] msm_serial: Make baud_code detection more dynamic

Quoted 26 lines · Bjorn Andersson
Quoted 25 lines · Stephen Boyd

[snip]

drivers/tty/serial/msm_serial.c +24 -0
+       unsigned int i, divisor;
+       const struct msm_baud_map *entry;
+       static const struct msm_baud_map table[] = {
+               { 1536, 0x00,  1 },
+               {  768, 0x11,  1 },
+               {  384, 0x22,  1 },
+               {  192, 0x33,  1 },
+               {   96, 0x44,  1 },
+               {   48, 0x55,  1 },
+               {   32, 0x66,  1 },
+               {   24, 0x77,  1 },
+               {   16, 0x88,  1 },
+               {   12, 0x99,  6 },
+               {    8, 0xaa,  6 },
+               {    6, 0xbb,  6 },
+               {    4, 0xcc,  6 },
+               {    3, 0xdd,  8 },
+               {    2, 0xee, 16 },
+               {    1, 0xff, 31 },
+       };
+
+       divisor = uart_get_divisor(port, baud);
+
+       for (i = 0, entry = table; i < ARRAY_SIZE(table); i++, entry++)
Quoted 9 lines

drivers/tty/serial/msm_serial.c static void msm_break_ctl(struct uart_port *port, int break_ctl) · line 361

Quoted 4 lines
drivers/tty/serial/msm_serial.c +4 -0
+               if (entry->divisor <= divisor)
+                       break;
+
+       return entry; /* Default to smallest divider */

Shouldn't matter, but you're not defaulting to the smallest divider. Your are defaulting to an undefined value, as entry will be off the array once i == ARRAY_SIZE().

Yes because the if condition will always be true. Perhaps that's too confusing? We could add a subtraction by 1 to make it more obvious.

for (i = 0; entry = table; i < ARRAY_SIZE(table) - 1; i++, entry++)
if (entry->divisor <= divisor)

		break;

return entry; /* Default to smallest divider*/

Signature · 2 lines
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation
author
#9 lore raw

PATCH 4/4 msm_serial: Send more than 1 character at a time on UARTDM

In reply to Stephen Boyd

UARTDM cores have a TX fifo that can accept more than one character per register write, but the msm_serial driver currently only supports 1 character mode. Add support for this mode of operation to speed up the transmit path on DM devices.

Signed-off-by Stephen Boyd <[email protected]>
---
 drivers/tty/serial/msm_serial.c | 51 ++++++++++++++++++++++++++---------------
 1 file changed, 32 insertions(+), 19 deletions(-)
drivers/tty/serial/msm_serial.c +32 -19
index cef8f40..97642ec 100644
@@ -195,10 +195,10 @@ static void handle_rx(struct uart_port *port)
 	tty_flip_buffer_push(tport);
 }
 
-static void reset_dm_count(struct uart_port *port)
+static void reset_dm_count(struct uart_port *port, int count)
 {
 	wait_for_xmitr(port);
-	msm_write(port, 1, UARTDM_NCF_TX);
+	msm_write(port, count, UARTDM_NCF_TX);
 	msm_read(port, UARTDM_NCF_TX);
 }
 

@@ -206,39 +206,52 @@ static void handle_tx(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
 	struct msm_port *msm_port = UART_TO_MSM(port);
-	int sent_tx;
+	unsigned int tx_count, num_chars;
+	unsigned int tf_pointer = 0;
+
+	tx_count = uart_circ_chars_pending(xmit);
+	tx_count = min3(tx_count, (unsigned int)UART_XMIT_SIZE - xmit->tail,
+			port->fifosize);
 
 	if (port->x_char) {
 		if (msm_port->is_uartdm)
-			reset_dm_count(port);
+			reset_dm_count(port, tx_count + 1);
 
 		msm_write(port, port->x_char,
 			  msm_port->is_uartdm ? UARTDM_TF : UART_TF);
 		port->icount.tx++;
 		port->x_char = 0;
+	} else if (tx_count && msm_port->is_uartdm) {
+		reset_dm_count(port, tx_count);
 	}
 
-	if (msm_port->is_uartdm)
-		reset_dm_count(port);
+	while (tf_pointer < tx_count) {
+		int i;
+		char buf[4] = { 0 };
+		unsigned int *bf = (unsigned int *)&buf;
 
-	while (msm_read(port, UART_SR) & UART_SR_TX_READY) {
-		if (uart_circ_empty(xmit)) {
-			/* disable tx interrupts */
-			msm_port->imr &= ~UART_IMR_TXLEV;
-			msm_write(port, msm_port->imr, UART_IMR);
+		if (!(msm_read(port, UART_SR) & UART_SR_TX_READY))
 			break;
-		}
-		msm_write(port, xmit->buf[xmit->tail],
-			  msm_port->is_uartdm ? UARTDM_TF : UART_TF);
 
 		if (msm_port->is_uartdm)
-			reset_dm_count(port);
+			num_chars = min(tx_count - tf_pointer, sizeof(buf));
+		else
+			num_chars = 1;
 
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		sent_tx = 1;
+		for (i = 0; i < num_chars; i++) {
+			buf[i] = xmit->buf[xmit->tail + i];
+			port->icount.tx++;
+		}
+
+		msm_write(port, *bf, msm_port->is_uartdm ? UARTDM_TF : UART_TF);
+		xmit->tail = (xmit->tail + num_chars) & (UART_XMIT_SIZE - 1);
+		tf_pointer += num_chars;
 	}
 
+	/* disable tx interrupts if nothing more to send */
+	if (uart_circ_empty(xmit))
+		msm_stop_tx(port);
+
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 }

@@ -757,7 +770,7 @@ static void msm_console_putchar(struct uart_port *port, int c)
 	struct msm_port *msm_port = UART_TO_MSM(port);
 
 	if (msm_port->is_uartdm)
-		reset_dm_count(port);
+		reset_dm_count(port, 1);
 
 	while (!(msm_read(port, UART_SR) & UART_SR_TX_READY))
 		;
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation
Acked-by on v1 4/4
#10 lore raw

Re: [PATCH 4/4] msm_serial: Send more than 1 character at a time on UARTDM

Quoted 9 lines · Stephen Boyd

UARTDM cores have a TX fifo that can accept more than one character per register write, but the msm_serial driver currently only supports 1 character mode. Add support for this mode of operation to speed up the transmit path on DM devices.

Signed-off-by Stephen Boyd <[email protected]>

---
drivers/tty/serial/msm_serial.c | 51 ++++++++++++++++++++++++++---------------

1 file changed, 32 insertions(+), 19 deletions(-)
Acked-by David Brown <[email protected]>
Signature · 3 lines
sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation
#11 lore raw
In reply to Stephen Boyd
Quoted 14 lines · Stephen Boyd

Here are a couple fixes and improvements to the msm_serial driver. The first two patches fix a bug on UARTDM devices and silence sparse warnings. The last two patches improve the baud code detection and increase the throughput on UARTDM devices.

After this it is rather trivial to add support for newer UARTDM devices via new compatible fields.

Stephen Boyd (4):
msm_serial: Fix NUL byte output on UARTDM
msm_serial: Fix sparse warnings
msm_serial: Make baud_code detection more dynamic
msm_serial: Send more than 1 character at a time on UARTDM

Quoted 3 lines

drivers/tty/serial/msm_serial.c | 180 ++++++++++++++++++++-------------------- drivers/tty/serial/msm_serial.h | 19 ++---

2 files changed, 97 insertions(+), 102 deletions(-)

Thanks for these patches. I'm glad to finally see these issues fixed.

David

Signature · 3 lines
sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation
Tested-by on the v1 series
#12 lore raw
In reply to Stephen Boyd

Hi,

Quoted 5 lines · Stephen Boyd

Here are a couple fixes and improvements to the msm_serial driver. The first two patches fix a bug on UARTDM devices and silence sparse warnings. The last two patches improve the baud code detection and increase the throughput on UARTDM devices.

Quoted 9 lines

After this it is rather trivial to add support for newer UARTDM devices via new compatible fields.

Stephen Boyd (4):
msm_serial: Fix NUL byte output on UARTDM
msm_serial: Fix sparse warnings
msm_serial: Make baud_code detection more dynamic
msm_serial: Send more than 1 character at a time on UARTDM

Thanks, It is working on 8074 based DragonBoard.

Tested-by Ivan T. Ivanov <[email protected]>
Quoted 4 lines
 drivers/tty/serial/msm_serial.c | 180 ++++++++++++++++++++--------------------
 drivers/tty/serial/msm_serial.h |  19 ++---
 2 files changed, 97 insertions(+), 102 deletions(-)