MMC: OMAP MSDI: fix broken PIO mode

PATCH New Paul Walmsley 4 participants 4 messages Aug 24, 2012 – Aug 27, 2012

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MMC, SD and SDIO OMAP MMC support

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Paul Walmsley

author

2012-08-24 06:00 UTC #0 lore raw

PATCH 1/1 MMC: OMAP MSDI: fix broken PIO mode

After commit 26b88520b80695a6fa5fd95b5d97c03f4daf87e0 ("mmc:
omap_hsmmc: remove private DMA API implementation"), the Nokia N800 here stopped booting:

[    2.086181] Waiting for root device /dev/mmcblk0p1...
[    2.324066] Unhandled fault: imprecise external abort (0x406) at 0x00000000
[    2.331451] Internal error: : 406 [#1] ARM
[    2.335784] Modules linked in:
[    2.339050] CPU: 0    Not tainted  (3.6.0-rc3 #60)
[    2.344146] PC is at default_idle+0x28/0x30
[    2.348602] LR is at trace_hardirqs_on_caller+0x15c/0x1b0

...

This turned out to be due to memory corruption caused by long-broken PIO code in drivers/mmc/host/omap.c. (Previously, this driver had been using DMA; but the above commit caused the MMC driver to fall back to PIO mode with an unmodified Kconfig.)

The PIO code, added with the rest of the driver in commit 730c9b7e6630f786fcec026fb11d2e6f2c90fdcb ("[MMC] Add OMAP MMC host driver"), confused bytes with 16-bit words. This bug caused memory located after the PIO transfer buffer to be corrupted with transfers larger than 32 bytes. The driver also did not increment the buffer pointer after the transfer occurred. This bug resulted in data corruption during any transfer larger than 64 bytes.

Signed-off-by Paul Walmsley <[email protected]>

Cc Juha Yrj?l? <[email protected]>

Cc Tony Lindgren <[email protected]>

Cc Carlos Aguiar <[email protected]>

Cc Russell King <[email protected]>

---
 drivers/mmc/host/omap.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

drivers/mmc/host/omap.c +11 -3

index 50e08f0..a5999a7 100644
@@ -668,7 +668,7 @@ mmc_omap_clk_timer(unsigned long data)
 static void
 mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
 {
-	int n;
+	int n, nwords;
 
 	if (host->buffer_bytes_left == 0) {
 		host->sg_idx++;

@@ -678,15 +678,23 @@ mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
 	n = 64;
 	if (n > host->buffer_bytes_left)
 		n = host->buffer_bytes_left;
+
+	nwords = n / 2;
+	nwords += n & 1; /* handle odd number of bytes to transfer */
+
 	host->buffer_bytes_left -= n;
 	host->total_bytes_left -= n;
 	host->data->bytes_xfered += n;
 
 	if (write) {
-		__raw_writesw(host->virt_base + OMAP_MMC_REG(host, DATA), host->buffer, n);
+		__raw_writesw(host->virt_base + OMAP_MMC_REG(host, DATA),
+			      host->buffer, nwords);
 	} else {
-		__raw_readsw(host->virt_base + OMAP_MMC_REG(host, DATA), host->buffer, n);
+		__raw_readsw(host->virt_base + OMAP_MMC_REG(host, DATA),
+			     host->buffer, nwords);
 	}
+
+	host->buffer += nwords;
 }
 
 static inline void mmc_omap_report_irq(u16 status)

Signature · 1 line

1.7.10.4

Felipe Balbi

2012-08-24 07:25 UTC #1 lore raw

PATCH 1/1 MMC: OMAP MSDI: fix broken PIO mode

Hi,

Quoted 28 lines · Paul Walmsley

After commit 26b88520b80695a6fa5fd95b5d97c03f4daf87e0 ("mmc:
omap_hsmmc: remove private DMA API implementation"), the Nokia N800 here stopped booting:
[    2.086181] Waiting for root device /dev/mmcblk0p1...
[    2.324066] Unhandled fault: imprecise external abort (0x406) at 0x00000000
[    2.331451] Internal error: : 406 [#1] ARM
[    2.335784] Modules linked in:
[    2.339050] CPU: 0    Not tainted  (3.6.0-rc3 #60)
[    2.344146] PC is at default_idle+0x28/0x30
[    2.348602] LR is at trace_hardirqs_on_caller+0x15c/0x1b0
...
This turned out to be due to memory corruption caused by long-broken PIO code in drivers/mmc/host/omap.c. (Previously, this driver had been using DMA; but the above commit caused the MMC driver to fall back to PIO mode with an unmodified Kconfig.)
The PIO code, added with the rest of the driver in commit 730c9b7e6630f786fcec026fb11d2e6f2c90fdcb ("[MMC] Add OMAP MMC host driver"), confused bytes with 16-bit words. This bug caused memory located after the PIO transfer buffer to be corrupted with transfers larger than 32 bytes. The driver also did not increment the buffer pointer after the transfer occurred. This bug resulted in data corruption during any transfer larger than 64 bytes.

Quoted 5 lines

Signed-off-by Paul Walmsley <[email protected]>
Cc Juha Yrj?l? <[email protected]>
Cc Tony Lindgren <[email protected]>
Cc Carlos Aguiar <[email protected]>
Cc Russell King <[email protected]>

this looks good to me, though I don't have how to test. FWIW:

Reviewed-by Felipe Balbi <[email protected]>

Quoted 45 lines

---
 drivers/mmc/host/omap.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

drivers/mmc/host/omap.c +11 -3

index 50e08f0..a5999a7 100644
@@ -668,7 +668,7 @@ mmc_omap_clk_timer(unsigned long data)
 static void
 mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
 {
-	int n;
+	int n, nwords;
 
 	if (host->buffer_bytes_left == 0) {
 		host->sg_idx++;

@@ -678,15 +678,23 @@ mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
 	n = 64;
 	if (n > host->buffer_bytes_left)
 		n = host->buffer_bytes_left;
+
+	nwords = n / 2;
+	nwords += n & 1; /* handle odd number of bytes to transfer */
+
 	host->buffer_bytes_left -= n;
 	host->total_bytes_left -= n;
 	host->data->bytes_xfered += n;
 
 	if (write) {
-		__raw_writesw(host->virt_base + OMAP_MMC_REG(host, DATA), host->buffer, n);
+		__raw_writesw(host->virt_base + OMAP_MMC_REG(host, DATA),
+			      host->buffer, nwords);
 	} else {
-		__raw_readsw(host->virt_base + OMAP_MMC_REG(host, DATA), host->buffer, n);
+		__raw_readsw(host->virt_base + OMAP_MMC_REG(host, DATA),
+			     host->buffer, nwords);
 	}
+
+	host->buffer += nwords;
 }
 
 static inline void mmc_omap_report_irq(u16 status)

Signature · 1 line

1.7.10.4

Signature · 8 lines

balbi
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Tony Lindgren

2012-08-24 15:53 UTC #2 lore raw

PATCH 1/1 MMC: OMAP MSDI: fix broken PIO mode

Quoted 4 lines · Felipe Balbi

this looks good to me, though I don't have how to test. FWIW:
Reviewed-by Felipe Balbi <[email protected]>

Works for me:

Tested-by Tony Lindgren <[email protected]>

Chris Ball

2012-08-27 22:42 UTC #3 lore raw

PATCH 1/1 MMC: OMAP MSDI: fix broken PIO mode

In reply to Paul Walmsley

Hi,

Quoted 27 lines · Paul Walmsley

After commit 26b88520b80695a6fa5fd95b5d97c03f4daf87e0 ("mmc:
omap_hsmmc: remove private DMA API implementation"), the Nokia N800 here stopped booting:
[    2.086181] Waiting for root device /dev/mmcblk0p1...
[    2.324066] Unhandled fault: imprecise external abort (0x406) at 0x00000000
[    2.331451] Internal error: : 406 [#1] ARM
[    2.335784] Modules linked in:
[    2.339050] CPU: 0    Not tainted  (3.6.0-rc3 #60)
[    2.344146] PC is at default_idle+0x28/0x30
[    2.348602] LR is at trace_hardirqs_on_caller+0x15c/0x1b0
...
This turned out to be due to memory corruption caused by long-broken PIO code in drivers/mmc/host/omap.c. (Previously, this driver had been using DMA; but the above commit caused the MMC driver to fall back to PIO mode with an unmodified Kconfig.)
The PIO code, added with the rest of the driver in commit 730c9b7e6630f786fcec026fb11d2e6f2c90fdcb ("[MMC] Add OMAP MMC host driver"), confused bytes with 16-bit words. This bug caused memory located after the PIO transfer buffer to be corrupted with transfers larger than 32 bytes. The driver also did not increment the buffer pointer after the transfer occurred. This bug resulted in data corruption during any transfer larger than 64 bytes.

Quoted 1 line

Signed-off-by Paul Walmsley <[email protected]>

Yuck. Thanks for tracking that down, Paul -- pushed to mmc-next for 3.6.

- Chris.

Signature · 2 lines

Chris Ball   <[email protected]>   <http://printf.net/>
One Laptop Per Child