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fsl_esdhc: Correcting esdhc timeout counter calculation

PATCH New Priyanka Jain 3 participants 4 messages Mar 3, 2011 – Mar 7, 2011 MMC, SD and SDIO

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Priyanka Jain

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#0 lore raw

PATCH v3 1/1 fsl_esdhc: Correcting esdhc timeout counter calculation

- Timeout counter value is set as DTOCV bits in SYSCTL register For counter value set as timeout,
Timeout period = (2^(timeout + 13)) SD Clock cycles

- As per 4.6.2.2 section of SD Card specification v2.00, host should cofigure timeout period value to minimum 0.25 sec.

- Number of SD Clock cycles for 0.25sec should be minimum

	(SD Clock/sec * 0.25 sec) SD Clock cycles
	= (mmc->tran_speed * 1/4) SD Clock cycles

- Calculating timeout based on

	(2^(timeout + 13)) >=  mmc->tran_speed * 1/4
	Taking log2 both the sides and rounding up to next power of 2
	=> timeout + 13 = log2(mmc->tran_speed/4) + 1
Signed-off-by Priyanka Jain <[email protected]>
Signed-off-by Andy Fleming <[email protected]>
Signed-off-by Kumar Gala <[email protected]>
Acked-by Mingkai Hu <[email protected]>

---
Changes for v3:
Including code changes of v1 as suggested by Stefano Babic

Changes for v2:
Added proper description as suggested by Wolfgang Denk

 drivers/mmc/fsl_esdhc.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)
drivers/mmc/fsl_esdhc.c +15 -1
index a368fe6..359d939 100644
@@ -207,7 +207,21 @@ static int esdhc_setup_data(struct mmc *mmc, struct mmc_data *data)
 	esdhc_write32(&regs->blkattr, data->blocks << 16 | data->blocksize);
 
 	/* Calculate the timeout period for data transactions */
-	timeout = fls(mmc->tran_speed/10) - 1;
+	/*
+	 * 1)Timeout period = (2^(timeout+13)) SD Clock cycles
+	 * 2)Timeout period should be minimum 0.250sec as per SD Card spec
+	 *  So, Number of SD Clock cycles for 0.25sec should be minimum
+	 *		(SD Clock/sec * 0.25 sec) SD Clock cycles
+	 *		= (mmc->tran_speed * 1/4) SD Clock cycles
+	 * As 1) >=  2)
+	 * => (2^(timeout+13)) >= mmc->tran_speed * 1/4
+	 * Taking log2 both the sides
+	 * => timeout + 13 >= log2(mmc->tran_speed/4)
+	 * Rounding up to next power of 2
+	 * => timeout + 13 = log2(mmc->tran_speed/4) + 1
+	 * => timeout + 13 = fls(mmc->tran_speed/4)
+	 */
+	timeout = fls(mmc->tran_speed/4);
 	timeout -= 13;
 
 	if (timeout > 14)
Signature · 1 line
1.6.5.6
#1 lore raw

PATCH v3 1/1 fsl_esdhc: Correcting esdhc timeout counter calculation

Quoted 24 lines · Priyanka Jain

- Timeout counter value is set as DTOCV bits in SYSCTL register For counter value set as timeout,
Timeout period = (2^(timeout + 13)) SD Clock cycles

- As per 4.6.2.2 section of SD Card specification v2.00, host should cofigure timeout period value to minimum 0.25 sec.

- Number of SD Clock cycles for 0.25sec should be minimum

	(SD Clock/sec * 0.25 sec) SD Clock cycles
	= (mmc->tran_speed * 1/4) SD Clock cycles

- Calculating timeout based on

	(2^(timeout + 13)) >=  mmc->tran_speed * 1/4
	Taking log2 both the sides and rounding up to next power of 2
	=> timeout + 13 = log2(mmc->tran_speed/4) + 1
Signed-off-by Priyanka Jain <[email protected]>
Signed-off-by Andy Fleming <[email protected]>
Signed-off-by Kumar Gala <[email protected]>
Acked-by Mingkai Hu <[email protected]>

---
Changes for v3:
Including code changes of v1 as suggested by Stefano Babic

Quoted 5 lines

Changes for v2:
Added proper description as suggested by Wolfgang Denk

drivers/mmc/fsl_esdhc.c | 16 +++++++++++++++-

1 files changed, 15 insertions(+), 1 deletions(-)

Stefano,

Got a chance to test on imx? Would like this fix in v2011.03

- k

#2 lore raw

PATCH v3 1/1 fsl_esdhc: Correcting esdhc timeout counter calculation

In reply to Priyanka Jain
Quoted 16 lines · Priyanka Jain

- Timeout counter value is set as DTOCV bits in SYSCTL register For counter value set as timeout,
Timeout period = (2^(timeout + 13)) SD Clock cycles

- As per 4.6.2.2 section of SD Card specification v2.00, host should cofigure timeout period value to minimum 0.25 sec.

- Number of SD Clock cycles for 0.25sec should be minimum

	(SD Clock/sec * 0.25 sec) SD Clock cycles
	= (mmc->tran_speed * 1/4) SD Clock cycles

- Calculating timeout based on

	(2^(timeout + 13)) >=  mmc->tran_speed * 1/4
	Taking log2 both the sides and rounding up to next power of 2
	=> timeout + 13 = log2(mmc->tran_speed/4) + 1
Quoted 5 lines
Signed-off-by Priyanka Jain <[email protected]>
Signed-off-by Andy Fleming <[email protected]>
Signed-off-by Kumar Gala <[email protected]>
Acked-by Mingkai Hu <[email protected]>

---

Tested on a i.MX51 board.

Tested-by Stefano Babic <[email protected]>

Best regards,
Stefano Babic

Signature · 5 lines
=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-0 Fax: +49-8142-66989-80  Email: office at denx.de
=====================================================================
Applied
#3 lore raw

PATCH v3 1/1 fsl_esdhc: Correcting esdhc timeout counter calculation

Quoted 23 lines · Stefano Babic
Quoted 16 lines · Priyanka Jain

- Timeout counter value is set as DTOCV bits in SYSCTL register For counter value set as timeout,
Timeout period = (2^(timeout + 13)) SD Clock cycles

- As per 4.6.2.2 section of SD Card specification v2.00, host should cofigure timeout period value to minimum 0.25 sec.

- Number of SD Clock cycles for 0.25sec should be minimum

	(SD Clock/sec * 0.25 sec) SD Clock cycles
	= (mmc->tran_speed * 1/4) SD Clock cycles

- Calculating timeout based on

	(2^(timeout + 13)) >=  mmc->tran_speed * 1/4
	Taking log2 both the sides and rounding up to next power of 2
	=> timeout + 13 = log2(mmc->tran_speed/4) + 1
Quoted 5 lines
Signed-off-by Priyanka Jain <[email protected]>
Signed-off-by Andy Fleming <[email protected]>
Signed-off-by Kumar Gala <[email protected]>
Acked-by Mingkai Hu <[email protected]>

---

Quoted 6 lines

Tested on a i.MX51 board.

Tested-by Stefano Babic <[email protected]>

Best regards,
Stefano Babic

thanks

applied.

- k