[PATCH 1/7] mmc_spi: allow setting of spi mode 3

[PATCH 1/7] mmc_spi: allow setting of spi mode 3

[Wolfgang Mües]

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

o allow the platform data structures to specify spi mode 3
  (if there is a pullup on the clock line or the spi hardware
   is not able to serve spi mode 0).

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_backported/drivers/mmc/host/mmc_spi.c 2_6_29_rc7_patch1_spi_mode_3/drivers/mmc/host/mmc_spi.c
--- 2_6_29_rc7_backported/drivers/mmc/host/mmc_spi.c	2009-03-04 02:05:22.000000000 +0100
+++ 2_6_29_rc7_patch1_spi_mode_3/drivers/mmc/host/mmc_spi.c	2009-03-11 12:58:47.000000000 +0100
@@ -1204,10 +1204,12 @@ static int mmc_spi_probe(struct spi_devi
 
 	/* MMC and SD specs only seem to care that sampling is on the
 	 * rising edge ... meaning SPI modes 0 or 3.  So either SPI mode
-	 * should be legit.  We'll use mode 0 since it seems to be a
-	 * bit less troublesome on some hardware ... unclear why.
+	 * should be legit.  We'll use mode 0 since the steady state is 0,
+	 * which is appropriate for hotplugging, unless the platform data
+	 * specify mode 3 (if hardware is not compatible to mode 0).
 	 */
-	spi->mode = SPI_MODE_0;
+	if (spi->mode != SPI_MODE_3)
+		spi->mode = SPI_MODE_0;
 	spi->bits_per_word = 8;
 
 	status = spi_setup(spi);

---
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
 
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Registriert beim AG Braunschweig HRA 13289
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Re: [PATCH 1/7] mmc_spi: allow setting of spi mode 3

[David Brownell]

On Wednesday 11 March 2009, Wolfgang Mües wrote:
> From: Wolfgang Muees <wolfgang.mues@auerswald.de>
> 
> o allow the platform data structures to specify spi mode 3
>   (if there is a pullup on the clock line or the spi hardware
>    is not able to serve spi mode 0).
> 
> Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>

Acked-by: David Brownell <dbrownell@users.sourceforge.net>


> ---
> 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_backported/drivers/mmc/host/mmc_spi.c 2_6_29_rc7_patch1_spi_mode_3/drivers/mmc/host/mmc_spi.c
> --- 2_6_29_rc7_backported/drivers/mmc/host/mmc_spi.c	2009-03-04 02:05:22.000000000 +0100
> +++ 2_6_29_rc7_patch1_spi_mode_3/drivers/mmc/host/mmc_spi.c	2009-03-11 12:58:47.000000000 +0100
> @@ -1204,10 +1204,12 @@ static int mmc_spi_probe(struct spi_devi
>  
>  	/* MMC and SD specs only seem to care that sampling is on the
>  	 * rising edge ... meaning SPI modes 0 or 3.  So either SPI mode
> -	 * should be legit.  We'll use mode 0 since it seems to be a
> -	 * bit less troublesome on some hardware ... unclear why.
> +	 * should be legit.  We'll use mode 0 since the steady state is 0,
> +	 * which is appropriate for hotplugging, unless the platform data
> +	 * specify mode 3 (if hardware is not compatible to mode 0).
>  	 */
> -	spi->mode = SPI_MODE_0;
> +	if (spi->mode != SPI_MODE_3)
> +		spi->mode = SPI_MODE_0;
>  	spi->bits_per_word = 8;
>  
>  	status = spi_setup(spi);
> 
> ---
> 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 1/7] mmc_spi: allow setting of spi mode 3

[Maxim Levitsky]

Small question:

Do linux SDHCI driver support SD 4 wire mode?

Or it uses the SPI mode.


Best regards,
	Maxim Levitsky

Re: [PATCH 1/7] mmc_spi: allow setting of spi mode 3

[Pierre Ossman]

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On Thu, 12 Mar 2009 14:50:32 +0200
Maxim Levitsky <maximlevitsky@gmail.com> wrote:

> Small question:
> 
> Do linux SDHCI driver support SD 4 wire mode?
> 
> Or it uses the SPI mode.
> 

I think you've managed to confuse yourself pretty good here. :)

This is a patch for the mmc_spi driver, which surprisingly enough is
for operating MMC/SD cards in SPI mode. ;)

The sdhci driver is completely unrelated (but yes, it supports 4-bit
mode).

Rgds
-- 
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