[PATCH 1/2] spi: check bits_per_word in spi_setup

[PATCH 1/2] spi: check bits_per_word in spi_setup

[Stefan Brüns]

This allows drivers for devices connected via SPI to check if the
controller supports a given bits_per_word value during setup.
Currently any BPW value is accepted durings setup, and transfers
are rejected later.

Signed-off-by: Stefan Brüns <stefan.bruens-vA1bhqPz9FBZXbeN9DUtxg@public.gmane.org>
---
 drivers/spi/spi.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index cf8b91b..98aaa31 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1740,6 +1740,20 @@ EXPORT_SYMBOL_GPL(spi_busnum_to_master);
  * other core methods are currently defined as inline functions.
  */
 
+static int __spi_validate_bits_per_word(struct spi_master *master, u8 bits_per_word)
+{
+	if (master->bits_per_word_mask) {
+		/* Only 32 bits fit in the mask */
+		if (bits_per_word > 32)
+			return -EINVAL;
+		if (!(master->bits_per_word_mask &
+				SPI_BPW_MASK(bits_per_word)))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
 /**
  * spi_setup - setup SPI mode and clock rate
  * @spi: the device whose settings are being modified
@@ -1798,6 +1812,9 @@ int spi_setup(struct spi_device *spi)
 	if (!spi->bits_per_word)
 		spi->bits_per_word = 8;
 
+	if (__spi_validate_bits_per_word(spi->master, spi->bits_per_word))
+		return -EINVAL;
+
 	if (!spi->max_speed_hz)
 		spi->max_speed_hz = spi->master->max_speed_hz;
 
@@ -1865,14 +1882,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 		    xfer->speed_hz > master->max_speed_hz)
 			xfer->speed_hz = master->max_speed_hz;
 
-		if (master->bits_per_word_mask) {
-			/* Only 32 bits fit in the mask */
-			if (xfer->bits_per_word > 32)
-				return -EINVAL;
-			if (!(master->bits_per_word_mask &
-					BIT(xfer->bits_per_word - 1)))
-				return -EINVAL;
-		}
+		if (__spi_validate_bits_per_word(master, xfer->bits_per_word))
+			return -EINVAL;
 
 		/*
 		 * SPI transfer length should be multiple of SPI word size
-- 
2.1.4

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[PATCH 2/2] staging/fbtft: use spi_setup instead of direct call to master->setup

[Stefan Brüns]

Avoid a crash, as master->setup may be NULL (e.g. xilinx controller).
Even if master->setup is set, spi_setup does several compatibility/
sanity checks which should not be skipped (fixes problems with
displays/controllers needing emulation for bits_per_word = 9).

Signed-off-by: Stefan Brüns <stefan.bruens-vA1bhqPz9FBZXbeN9DUtxg@public.gmane.org>
---
 drivers/staging/fbtft/fb_watterott.c | 4 ++--
 drivers/staging/fbtft/fbtft-core.c   | 4 ++--
 drivers/staging/fbtft/flexfb.c       | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

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;
diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index 9cc8141..ba08da3 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -1434,12 +1434,12 @@ 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);
+		ret = spi_setup(par->spi);
 		if (ret) {
 			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);
+			ret = spi_setup(par->spi);
 			if (ret)
 				goto out_release;
 			/* allocate buffer with room for dc bits */
diff --git a/drivers/staging/fbtft/flexfb.c b/drivers/staging/fbtft/flexfb.c
index 2c4ce07..fecf486 100644
--- a/drivers/staging/fbtft/flexfb.c
+++ b/drivers/staging/fbtft/flexfb.c
@@ -440,12 +440,12 @@ 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);
+			ret = spi_setup(sdev);
 			if (ret) {
 				dev_warn(dev,
 					"9-bit SPI not available, emulating using 8-bit.\n");
 				sdev->bits_per_word = 8;
-				ret = sdev->master->setup(sdev);
+				ret = spi_setup(sdev);
 				if (ret)
 					goto out_release;
 				/* allocate buffer with room for dc bits */
-- 
2.1.4

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Re: [PATCH 0/2] Fix displays requiring 9 bit transfers on RPi

[Stefan Bruens]

Hi,

any comments on these two patches?

Kind regards,

Stefan

On Tuesday 11 August 2015 09:27:49 you wrote:
> Some displays need 9 bit long SPI transfers (Command/Data flag plus
> 8 bit data). FBTFT has emulation code in case the controller only
> supports 8 bit transfers, but this is only used if the controller
> setup function report an error if bits_per_word is set to 9.
> 
> Report unsupported bits_per_word settings in spi_setup Currently the
> SPI core only checks bits_per_word on transfer, but not on setup.
> 
> Replace invocations of master->setup(...) with spi_setup(...).
> 
> Tested on RPi B with an Ilitek9341 based TFT display in 9 bit mode.
> 
> Stefan Brüns (2):
>   spi: check bits_per_word in spi_setup
>   staging/fbtft: use spi_setup instead of direct call to master->setup
> 
>  drivers/spi/spi.c                    | 27 +++++++++++++++++++--------
>  drivers/staging/fbtft/fb_watterott.c |  4 ++--
>  drivers/staging/fbtft/fbtft-core.c   |  4 ++--
>  drivers/staging/fbtft/flexfb.c       |  4 ++--
>  4 files changed, 25 insertions(+), 14 deletions(-)

-- 
Stefan Brüns  /  Bergstraße 21  /  52062 Aachen
home: +49 241 53809034     mobile: +49 151 50412019
work: +49 2405 49936-424
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Re: [PATCH 0/2] Fix displays requiring 9 bit transfers on RPi

[Brüns, Stefan]

Hi,

any comments on these two patches, please?

Kind regards,

Stefan


On Tuesday, August 11, 2015 09:27:49 you wrote:
> Some displays need 9 bit long SPI transfers (Command/Data flag plus
> 8 bit data). FBTFT has emulation code in case the controller only
> supports 8 bit transfers, but this is only used if the controller
> setup function report an error if bits_per_word is set to 9.
> 
> Report unsupported bits_per_word settings in spi_setup Currently the
> SPI core only checks bits_per_word on transfer, but not on setup.
> 
> Replace invocations of master->setup(...) with spi_setup(...).
> 
> Tested on RPi B with an Ilitek9341 based TFT display in 9 bit mode.
> 
> Stefan Brüns (2):
>   spi: check bits_per_word in spi_setup
>   staging/fbtft: use spi_setup instead of direct call to master->setup
> 
>  drivers/spi/spi.c                    | 27 +++++++++++++++++++--------
>  drivers/staging/fbtft/fb_watterott.c |  4 ++--
>  drivers/staging/fbtft/fbtft-core.c   |  4 ++--
>  drivers/staging/fbtft/flexfb.c       |  4 ++--
>  4 files changed, 25 insertions(+), 14 deletions(-)

-- 
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home: +49 241 53809034     mobile: +49 151 50412019
work: +49 2405 49936-424--
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