[PATCH 0/2] staging: fbtft: Avoid calling SPI master setup directly

[PATCH 0/2] staging: fbtft: Avoid calling SPI master setup directly

[Stefan Wahren]

This patch series fixes issues caused by calling SPI master setup function
directly.

Changes since RFC:
  * use only bits_per_word_mask for 9-bit support detection 
    (suggested by Noralf Trønnes)
  * change patch order

Stefan Wahren (2):
  staging: fbtft: fix 9-bit SPI support detection
  staging: fbtft: replace master->setup() with spi_setup()

 drivers/staging/fbtft/fb_uc1611.c    |    2 +-
 drivers/staging/fbtft/fb_watterott.c |    4 ++--
 drivers/staging/fbtft/fbtft-core.c   |   10 +++-------
 drivers/staging/fbtft/flexfb.c       |   11 ++++-------
 4 files changed, 10 insertions(+), 17 deletions(-)

-- 
1.7.9.5

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

[Stefan Wahren]

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@i2se.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

[PATCH 2/2] staging: fbtft: replace master->setup() with spi_setup()

[Stefan Wahren]

Calling the setup of the SPI master directly causes a NULL pointer
dereference with master drivers without a separate setup function.
This problem is reproduceable on ARM MXS platform.

So fix this issue by using spi_setup() instead.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 drivers/staging/fbtft/fb_uc1611.c    |    2 +-
 drivers/staging/fbtft/fb_watterott.c |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/fbtft/fb_uc1611.c b/drivers/staging/fbtft/fb_uc1611.c
index 32f3a9d..5cafa50 100644
--- a/drivers/staging/fbtft/fb_uc1611.c
+++ b/drivers/staging/fbtft/fb_uc1611.c
@@ -76,7 +76,7 @@ static int init_display(struct fbtft_par *par)
 
 	/* Set CS active high */
 	par->spi->mode |= SPI_CS_HIGH;
-	ret = par->spi->master->setup(par->spi);
+	ret = spi_setup(par->spi);
 	if (ret) {
 		dev_err(par->info->device, "Could not set SPI_CS_HIGH\n");
 		return ret;
diff --git a/drivers/staging/fbtft/fb_watterott.c b/drivers/staging/fbtft/fb_watterott.c
index 88fb2c0..8eae6ef 100644
--- a/drivers/staging/fbtft/fb_watterott.c
+++ b/drivers/staging/fbtft/fb_watterott.c
@@ -169,7 +169,7 @@ static int init_display(struct fbtft_par *par)
 	/* enable SPI interface by having CS and MOSI low during reset */
 	save_mode = par->spi->mode;
 	par->spi->mode |= SPI_CS_HIGH;
-	ret = par->spi->master->setup(par->spi); /* set CS inactive low */
+	ret = spi_setup(par->spi); /* set CS inactive low */
 	if (ret) {
 		dev_err(par->info->device, "Could not set SPI_CS_HIGH\n");
 		return ret;
@@ -180,7 +180,7 @@ static int init_display(struct fbtft_par *par)
 	par->fbtftops.reset(par);
 	mdelay(1000);
 	par->spi->mode = save_mode;
-	ret = par->spi->master->setup(par->spi);
+	ret = spi_setup(par->spi);
 	if (ret) {
 		dev_err(par->info->device, "Could not restore SPI mode\n");
 		return ret;
-- 
1.7.9.5

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

[Noralf Trønnes]

Den 25.08.2015 23:04, skrev Stefan Wahren:
> 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@i2se.com>
> ---
>   drivers/staging/fbtft/fbtft-core.c |   10 +++-------
>   drivers/staging/fbtft/flexfb.c     |   11 ++++-------
>   2 files changed, 7 insertions(+), 14 deletions(-)

Thanks Stefan.

Both patches:
Acked-by: Noralf Trønnes <noralf@tronnes.org>