linux-kernel - [PATCH 1/2] staging: fbtft: fix 9-bit SPI support detection

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Date:	Tue, 25 Aug 2015 21:04:11 +0000
From:	Stefan Wahren <stefan.wahren@...e.com>
To:	Noralf Trønnes <noralf@...nnes.org>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Henri Chain <henri.chain@...ves.ec-nantes.fr>,
	linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
	Stefan Wahren <stefan.wahren@...e.com>
Subject: [PATCH 1/2] staging: fbtft: fix 9-bit SPI support detection

Since the result of the setup function isn't adequate to check
9-bit SPI support, we better check bits_per_word_mask. Btw this
change avoids a NULL pointer dereference with master drivers
without a separate setup function.

Signed-off-by: Stefan Wahren <stefan.wahren@...e.com>
---
 drivers/staging/fbtft/fbtft-core.c |   10 +++-------
 drivers/staging/fbtft/flexfb.c     |   11 ++++-------
 2 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index 23392eb..7f5fa3d 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -1436,15 +1436,11 @@ int fbtft_probe_common(struct fbtft_display *display,
 
 	/* 9-bit SPI setup */
 	if (par->spi && display->buswidth == 9) {
-		par->spi->bits_per_word = 9;
-		ret = par->spi->master->setup(par->spi);
-		if (ret) {
+		if (par->spi->master->bits_per_word_mask & SPI_BPW_MASK(9)) {
+			par->spi->bits_per_word = 9;
+		} else {
 			dev_warn(&par->spi->dev,
 				"9-bit SPI not available, emulating using 8-bit.\n");
-			par->spi->bits_per_word = 8;
-			ret = par->spi->master->setup(par->spi);
-			if (ret)
-				goto out_release;
 			/* allocate buffer with room for dc bits */
 			par->extra = devm_kzalloc(par->info->device,
 				par->txbuf.len + (par->txbuf.len / 8) + 8,
diff --git a/drivers/staging/fbtft/flexfb.c b/drivers/staging/fbtft/flexfb.c
index c763efc..3f380a0 100644
--- a/drivers/staging/fbtft/flexfb.c
+++ b/drivers/staging/fbtft/flexfb.c
@@ -463,15 +463,12 @@ static int flexfb_probe_common(struct spi_device *sdev,
 			}
 			par->fbtftops.write_register = fbtft_write_reg8_bus9;
 			par->fbtftops.write_vmem = fbtft_write_vmem16_bus9;
-			sdev->bits_per_word = 9;
-			ret = sdev->master->setup(sdev);
-			if (ret) {
+			if (par->spi->master->bits_per_word_mask
+			    & SPI_BPW_MASK(9)) {
+				par->spi->bits_per_word = 9;
+			} else {
 				dev_warn(dev,
 					"9-bit SPI not available, emulating using 8-bit.\n");
-				sdev->bits_per_word = 8;
-				ret = sdev->master->setup(sdev);
-				if (ret)
-					goto out_release;
 				/* allocate buffer with room for dc bits */
 				par->extra = devm_kzalloc(par->info->device,
 						par->txbuf.len + (par->txbuf.len / 8) + 8,
-- 
1.7.9.5

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