[PATCH 3/7] mmc_spi: adjust for delayed data token response

[PATCH 3/7] mmc_spi: adjust for delayed data token response

[Wolfgang Mües]

From: Wolfgang Muees <wolfgang.mues@auerswald.de>

o some cards are not able to send the data token in time, but
  miss the time frame for some bits(!). So synchronize to the
  start of the token.

Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>

---
This is one of a line of patches to enhance the usability of
the mmc spi host port driver from "don't work with most SD cards"
to "work with nearly all SD cards" (including those ugly cards
with non-byte-aligned responses).

diff -uprN 2_6_29_rc7_patch2_wait_16bytes_response/drivers/mmc/host/mmc_spi.c 2_6_29_rc7_patch3_delayed_data_response/drivers/mmc/host/mmc_spi.c
--- 2_6_29_rc7_patch2_wait_16bytes_response/drivers/mmc/host/mmc_spi.c	2009-03-11 13:00:06.000000000 +0100
+++ 2_6_29_rc7_patch3_delayed_data_response/drivers/mmc/host/mmc_spi.c	2009-03-11 13:42:48.000000000 +0100
@@ -612,6 +612,7 @@ mmc_spi_writeblock(struct mmc_spi_host *
 	struct spi_device	*spi = host->spi;
 	int			status, i;
 	struct scratch		*scratch = host->data;
+	u32			pattern;
 
 	if (host->mmc->use_spi_crc)
 		scratch->crc_val = cpu_to_be16(
@@ -639,8 +640,23 @@ mmc_spi_writeblock(struct mmc_spi_host *
 	 * doesn't necessarily tell whether the write operation succeeded;
 	 * it just says if the transmission was ok and whether *earlier*
 	 * writes succeeded; see the standard.
-	 */
-	switch (SPI_MMC_RESPONSE_CODE(scratch->status[0])) {
+	 *
+	 * In practice, there are (even modern SDHC-)Cards which need
+	 * some bits to send the response, so we have to cope with this
+	 * situation and check the response bit-by-bit. Arggh!!!
+	 */
+	pattern  = scratch->status[0] << 24;
+	pattern |= scratch->status[1] << 16;
+	pattern |= scratch->status[2] << 8;
+	pattern |= scratch->status[3];
+
+	/* left-adjust to leading 0 bit */
+	while (pattern & 0x80000000)
+		pattern <<= 1;
+	/* right-adjust for pattern matching. Code is in bit 4..0 now. */
+	pattern >>= 27;
+
+	switch (pattern) {
 	case SPI_RESPONSE_ACCEPTED:
 		status = 0;
 		break;
@@ -671,8 +687,8 @@ mmc_spi_writeblock(struct mmc_spi_host *
 	/* Return when not busy.  If we didn't collect that status yet,
 	 * we'll need some more I/O.
 	 */
-	for (i = 1; i < sizeof(scratch->status); i++) {
-		if (scratch->status[i] != 0)
+	for (i = 4; i < sizeof(scratch->status); i++) {
+		if (scratch->status[i] & 0x01)
 			return 0;
 	}
 	return mmc_spi_wait_unbusy(host, timeout);

---
regards

i. A. Wolfgang Mües
-- 
Auerswald GmbH & Co. KG
Hardware Development
Telefon: +49 (0)5306 9219 0
Telefax: +49 (0)5306 9219 94 
E-Mail: Wolfgang.Mues@Auerswald.de
Web: http://www.auerswald.de
 
--------------------------------------------------------------
Auerswald GmbH & Co. KG, Vor den Grashöfen 1, 38162 Cremlingen
Registriert beim AG Braunschweig HRA 13289
p.h.G Auerswald Geschäftsführungsges. mbH
Registriert beim AG Braunschweig HRB 7463
Geschäftsführer: Dipl-Ing. Gerhard Auerswald

Re: [PATCH 3/7] mmc_spi: adjust for delayed data token response

[David Brownell]

On Wednesday 11 March 2009, Wolfgang Mües wrote:
> @@ -639,8 +640,23 @@ mmc_spi_writeblock(struct mmc_spi_host *
>  	 * doesn't necessarily tell whether the write operation succeeded;
>  	 * it just says if the transmission was ok and whether *earlier*
>  	 * writes succeeded; see the standard.
> -	 */
> -	switch (SPI_MMC_RESPONSE_CODE(scratch->status[0])) {
> +	 *
> +	 * In practice, there are (even modern SDHC-)Cards which need
> +	 * some bits to send the response, so we have to cope with this

All hardware needs some bits to send binary data!!

Do you mean "which don't send byte-aligned responses,
contrary to MMC/SD/SDIO specifications"?


> +	 * situation and check the response bit-by-bit. Arggh!!!
> +	 */
> +	pattern  = scratch->status[0] << 24;
> +	pattern |= scratch->status[1] << 16;
> +	pattern |= scratch->status[2] << 8;
> +	pattern |= scratch->status[3];
> +
> +	/* left-adjust to leading 0 bit */
> +	while (pattern & 0x80000000)
> +		pattern <<= 1;
> +	/* right-adjust for pattern matching. Code is in bit 4..0 now. */
> +	pattern >>= 27;
> +
> +	switch (pattern) {
>  	case SPI_RESPONSE_ACCEPTED:
>  		status = 0;
>  		break;
> @@ -671,8 +687,8 @@ mmc_spi_writeblock(struct mmc_spi_host *
>  	/* Return when not busy.  If we didn't collect that status yet,
>  	 * we'll need some more I/O.
>  	 */
> -	for (i = 1; i < sizeof(scratch->status); i++) {
> -		if (scratch->status[i] != 0)
> +	for (i = 4; i < sizeof(scratch->status); i++) {
> +		if (scratch->status[i] & 0x01)

I think I see why you skip four bytes, since you used
them above.  But why change the "!= 0" test?


>  			return 0;
>  	}
>  	return mmc_spi_wait_unbusy(host, timeout);
> 
> ---
> regards
> 

Re: [PATCH 3/7] mmc_spi: adjust for delayed data token response

[Wolfgang Mües]

David,
Am Mittwoch, 11. März 2009 schrieb David Brownell:
> All hardware needs some bits to send binary data!!
>
> Do you mean "which don't send byte-aligned responses,
> contrary to MMC/SD/SDIO specifications"?

No. The specification states that the response from the card after a whole 
data block is received is IMMEDIATELY, with 0 bits delay. Not every card is 
able to do this all the time.

My comment is a little bit missleading, yes.

best regards
 
i. A. Wolfgang Mües
-- 
Auerswald GmbH & Co. KG
Hardware Development
Telefon: +49 (0)5306 9219 0
Telefax: +49 (0)5306 9219 94 
E-Mail: Wolfgang.Mues@Auerswald.de
Web: http://www.auerswald.de
 
--------------------------------------------------------------
Auerswald GmbH & Co. KG, Vor den Grashöfen 1, 38162 Cremlingen
Registriert beim AG Braunschweig HRA 13289
p.h.G Auerswald Geschäftsführungsges. mbH
Registriert beim AG Braunschweig HRB 7463
Geschäftsführer: Dipl-Ing. Gerhard Auerswald

Re: [PATCH 3/7] mmc_spi: adjust for delayed data token response

[David Brownell]

On Thursday 12 March 2009, Wolfgang Mües wrote:
> David,
> Am Mittwoch, 11. März 2009 schrieb David Brownell:
> > All hardware needs some bits to send binary data!!
> >
> > Do you mean "which don't send byte-aligned responses,
> > contrary to MMC/SD/SDIO specifications"?
> 
> No. The specification states that the response from the card after a whole 
> data block is received is IMMEDIATELY, with 0 bits delay. Not every card is 
> able to do this all the time.
> 
> My comment is a little bit missleading, yes.

Well, aligned to zero bytes is the same as "immediately".  ;)

And that description matches up with your other patch.  But
either way, the comment was confusing.

- Dave

Re: [PATCH 3/7] mmc_spi: adjust for delayed data token response

[Pierre Ossman]

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On Thu, 12 Mar 2009 01:24:37 -0800
David Brownell <david-b@pacbell.net> wrote:

> 
> Well, aligned to zero bytes is the same as "immediately".  ;)
> 
> And that description matches up with your other patch.  But
> either way, the comment was confusing.
> 

I guess we need a new one then to avoid this happening again. ;)

And what about that changed if-clause?

Rgds
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