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

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Date:	Wed, 11 Mar 2009 14:13:15 +0100
From:	Wolfgang Mües <wolfgang.mues@...rswald.de>
To:	Pierre Ossman <drzeus@...eus.cx>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Matt Fleming" <matt@...sole-pimps.org>,
	"David Brownell" <dbrownell@...rs.sourceforge.net>,
	"Mike Frysinger" <vapier.adi@...il.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/7] mmc_spi: allow setting of spi mode 3

From: Wolfgang Muees <wolfgang.mues@...rswald.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@...rswald.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
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