[PATCH RFC 0/2] staging: fbtft: fix 9-bit SPI support

[PATCH RFC 0/2] staging: fbtft: fix 9-bit SPI support

[Stefan Wahren]

This patch series fixes the 9-bit SPI support of fbtft.

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

 drivers/staging/fbtft/fb_uc1611.c    |    2 +-
 drivers/staging/fbtft/fb_watterott.c |    4 ++--
 drivers/staging/fbtft/fbtft-core.c   |   11 +++++++++--
 drivers/staging/fbtft/flexfb.c       |   11 +++++++++--
 4 files changed, 21 insertions(+), 7 deletions(-)

-- 
1.7.9.5

[PATCH RFC 1/2] 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 ++--
 drivers/staging/fbtft/fbtft-core.c   |    4 ++--
 drivers/staging/fbtft/flexfb.c       |    4 ++--
 4 files changed, 7 insertions(+), 7 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;
diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index 23392eb..3638554 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -1437,12 +1437,12 @@ 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 c763efc..09fd15d 100644
--- a/drivers/staging/fbtft/flexfb.c
+++ b/drivers/staging/fbtft/flexfb.c
@@ -464,12 +464,12 @@ 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 */
-- 
1.7.9.5

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

[Stefan Wahren]

Since bits_per_word isn't usually checked during SPI setup the 9-bit
support must be checked manually.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 drivers/staging/fbtft/fbtft-core.c |    7 +++++++
 drivers/staging/fbtft/flexfb.c     |    7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index 3638554..bd71487 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -1438,6 +1438,13 @@ int fbtft_probe_common(struct fbtft_display *display,
 	if (par->spi && display->buswidth == 9) {
 		par->spi->bits_per_word = 9;
 		ret = spi_setup(par->spi);
+		if (!ret) {
+			struct spi_master *ma = par->spi->master;
+
+			if (!(ma->bits_per_word_mask & SPI_BPW_MASK(9)))
+				ret = -EINVAL;
+		}
+
 		if (ret) {
 			dev_warn(&par->spi->dev,
 				"9-bit SPI not available, emulating using 8-bit.\n");
diff --git a/drivers/staging/fbtft/flexfb.c b/drivers/staging/fbtft/flexfb.c
index 09fd15d..a54a8d9 100644
--- a/drivers/staging/fbtft/flexfb.c
+++ b/drivers/staging/fbtft/flexfb.c
@@ -465,6 +465,13 @@ static int flexfb_probe_common(struct spi_device *sdev,
 			par->fbtftops.write_vmem = fbtft_write_vmem16_bus9;
 			sdev->bits_per_word = 9;
 			ret = spi_setup(sdev);
+			if (!ret) {
+				struct spi_master *ma = par->spi->master;
+
+				if (!(ma->bits_per_word_mask & SPI_BPW_MASK(9)))
+					ret = -EINVAL;
+			}
+
 			if (ret) {
 				dev_warn(dev,
 					"9-bit SPI not available, emulating using 8-bit.\n");
-- 
1.7.9.5

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

[Noralf Trønnes]

Den 24.08.2015 20:33, skrev Stefan Wahren:
> Since bits_per_word isn't usually checked during SPI setup the 9-bit
> support must be checked manually.
>
> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> ---
>   drivers/staging/fbtft/fbtft-core.c |    7 +++++++
>   drivers/staging/fbtft/flexfb.c     |    7 +++++++
>   2 files changed, 14 insertions(+)
>
> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
> index 3638554..bd71487 100644
> --- a/drivers/staging/fbtft/fbtft-core.c
> +++ b/drivers/staging/fbtft/fbtft-core.c
> @@ -1438,6 +1438,13 @@ int fbtft_probe_common(struct fbtft_display *display,
>   	if (par->spi && display->buswidth == 9) {
>   		par->spi->bits_per_word = 9;
>   		ret = spi_setup(par->spi);
> +		if (!ret) {
> +			struct spi_master *ma = par->spi->master;
> +
> +			if (!(ma->bits_per_word_mask & SPI_BPW_MASK(9)))
> +				ret = -EINVAL;
> +		}
> +
>   		if (ret) {

There's no point in calling spi_setup() when it doesn't check bits_per_word.
Apparently this changed with the commit:
spi: convert drivers to use bits_per_word_mask.
This has not been detected earlier, because FBTFT was previously mostly
used on the Raspberry Pi which had a downstream SPI driver that did this 
check.

How about this:

-                par->spi->bits_per_word = 9;
-                ret = par->spi->master->setup(par->spi);
+                if (par->spi->master->bits_per_word_mask & 
SPI_BPW_MASK(9)) {
+                        par->spi->bits_per_word = 9;
-                if (ret) {
+                } 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,

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

[Stefan Wahren]

> Noralf Trønnes <noralf@tronnes.org> hat am 25. August 2015 um 00:00
> geschrieben:
>
>
>
> Den 24.08.2015 20:33, skrev Stefan Wahren:
> > Since bits_per_word isn't usually checked during SPI setup the 9-bit
> > support must be checked manually.
> >
> > Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> > ---
> > drivers/staging/fbtft/fbtft-core.c | 7 +++++++
> > drivers/staging/fbtft/flexfb.c | 7 +++++++
> > 2 files changed, 14 insertions(+)
> >
> > diff --git a/drivers/staging/fbtft/fbtft-core.c
> > b/drivers/staging/fbtft/fbtft-core.c
> > index 3638554..bd71487 100644
> > --- a/drivers/staging/fbtft/fbtft-core.c
> > +++ b/drivers/staging/fbtft/fbtft-core.c
> > @@ -1438,6 +1438,13 @@ int fbtft_probe_common(struct fbtft_display *display,
> > if (par->spi && display->buswidth == 9) {
> > par->spi->bits_per_word = 9;
> > ret = spi_setup(par->spi);
> > + if (!ret) {
> > + struct spi_master *ma = par->spi->master;
> > +
> > + if (!(ma->bits_per_word_mask & SPI_BPW_MASK(9)))
> > + ret = -EINVAL;
> > + }
> > +
> > if (ret) {
>
> There's no point in calling spi_setup() when it doesn't check bits_per_word.

If checking of bits_per_word is the only intention of the setup call, then i
agree.
But i'm not sure it is safe to remove the setup call complete.

Couldn't this cause regressions since there is no common spi setup call for all
drivers?

> Apparently this changed with the commit:
> spi: convert drivers to use bits_per_word_mask.
> This has not been detected earlier, because FBTFT was previously mostly
> used on the Raspberry Pi which had a downstream SPI driver that did this
> check.
>
> How about this:
>
> - par->spi->bits_per_word = 9;
> - ret = par->spi->master->setup(par->spi);
> + if (par->spi->master->bits_per_word_mask &
> SPI_BPW_MASK(9)) {
> + par->spi->bits_per_word = 9;
> - if (ret) {
> + } else {
> dev_warn(&par->spi->dev,
> "9-bit SPI not available, emulating
> using 8-bit.\n");
> - par->spi->bits_per_word = 8;

I think this assignment should stay.

> - 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,
>

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

[Noralf Trønnes]

Den 25.08.2015 19:34, skrev Stefan Wahren:
>> Noralf Trønnes <noralf@tronnes.org> hat am 25. August 2015 um 00:00
>> geschrieben:
>>
>>
>>
>> Den 24.08.2015 20:33, skrev Stefan Wahren:
>>> Since bits_per_word isn't usually checked during SPI setup the 9-bit
>>> support must be checked manually.
>>>
>>> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
>>> ---
>>> drivers/staging/fbtft/fbtft-core.c | 7 +++++++
>>> drivers/staging/fbtft/flexfb.c | 7 +++++++
>>> 2 files changed, 14 insertions(+)
>>>
>>> diff --git a/drivers/staging/fbtft/fbtft-core.c
>>> b/drivers/staging/fbtft/fbtft-core.c
>>> index 3638554..bd71487 100644
>>> --- a/drivers/staging/fbtft/fbtft-core.c
>>> +++ b/drivers/staging/fbtft/fbtft-core.c
>>> @@ -1438,6 +1438,13 @@ int fbtft_probe_common(struct fbtft_display *display,
>>> if (par->spi && display->buswidth == 9) {
>>> par->spi->bits_per_word = 9;
>>> ret = spi_setup(par->spi);
>>> + if (!ret) {
>>> + struct spi_master *ma = par->spi->master;
>>> +
>>> + if (!(ma->bits_per_word_mask & SPI_BPW_MASK(9)))
>>> + ret = -EINVAL;
>>> + }
>>> +
>>> if (ret) {
>> There's no point in calling spi_setup() when it doesn't check bits_per_word.
> If checking of bits_per_word is the only intention of the setup call, then i
> agree.
> But i'm not sure it is safe to remove the setup call complete.
>
> Couldn't this cause regressions since there is no common spi setup call for all
> drivers?

spi_add_device() calls spi_setup() for all spi devices so it's already done.
If spi_setup() did something with bits_per_word, then I agree that we should
call it in the 9-bit case. But this is not the case, and it's possible to
change bits_per_word per transfer later, so I can't see that this is needed.

>> Apparently this changed with the commit:
>> spi: convert drivers to use bits_per_word_mask.
>> This has not been detected earlier, because FBTFT was previously mostly
>> used on the Raspberry Pi which had a downstream SPI driver that did this
>> check.
>>
>> How about this:
>>
>> - par->spi->bits_per_word = 9;
>> - ret = par->spi->master->setup(par->spi);
>> + if (par->spi->master->bits_per_word_mask &
>> SPI_BPW_MASK(9)) {
>> + par->spi->bits_per_word = 9;
>> - if (ret) {
>> + } else {
>> dev_warn(&par->spi->dev,
>> "9-bit SPI not available, emulating
>> using 8-bit.\n");
>> - par->spi->bits_per_word = 8;
> I think this assignment should stay.

Not needed since we haven't changed the default set by spi_setup():
         if (!spi->bits_per_word)
                 spi->bits_per_word = 8;

Callchain for DT registered spi devices:
spi_register_master->of_register_spi_devices->of_register_spi_device->
spi_add_device->spi_setup