[PATCH 1/2] drm/bridge: it66121: Initialize {device,vendor}_ids

[PATCH 1/2] drm/bridge: it66121: Initialize {device,vendor}_ids

[Paul Cercueil]

These two arrays are populated with data read from the I2C device
through regmap_read(), and the data is then compared with hardcoded
vendor/product ID values of supported chips.

However, the return value of regmap_read() was never checked. This is
fine, as long as the two arrays are zero-initialized, so that we don't
compare the vendor/product IDs against whatever garbage is left on the
stack.

Address this issue by zero-initializing these two arrays.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/gpu/drm/bridge/ite-it66121.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
index 2f2a09adb4bc..b130d01147c6 100644
--- a/drivers/gpu/drm/bridge/ite-it66121.c
+++ b/drivers/gpu/drm/bridge/ite-it66121.c
@@ -889,7 +889,7 @@ static irqreturn_t it66121_irq_threaded_handler(int irq, void *dev_id)
 static int it66121_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
-	u32 vendor_ids[2], device_ids[2], revision_id;
+	u32 revision_id, vendor_ids[2] = { 0 }, device_ids[2] = { 0 };
 	struct device_node *ep;
 	int ret;
 	struct it66121_ctx *ctx;
-- 
2.33.0

[PATCH 2/2] drm/bridge: it66121: Wait for next bridge to be probed

[Paul Cercueil]

If run before the next bridge is initialized, of_drm_find_bridge() will
give us a NULL pointer.

If that's the case, return -EPROBE_DEFER; we may have more luck next
time.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/gpu/drm/bridge/ite-it66121.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
index b130d01147c6..9dc41a7b9136 100644
--- a/drivers/gpu/drm/bridge/ite-it66121.c
+++ b/drivers/gpu/drm/bridge/ite-it66121.c
@@ -924,6 +924,9 @@ static int it66121_probe(struct i2c_client *client,
 	ctx->next_bridge = of_drm_find_bridge(ep);
 	of_node_put(ep);
 
+	if (!ctx->next_bridge)
+		return -EPROBE_DEFER;
+
 	i2c_set_clientdata(client, ctx);
 	mutex_init(&ctx->lock);
 
-- 
2.33.0

Re: [PATCH 2/2] drm/bridge: it66121: Wait for next bridge to be probed

[Neil Armstrong]

On 27/08/2021 18:39, Paul Cercueil wrote:
> If run before the next bridge is initialized, of_drm_find_bridge() will
> give us a NULL pointer.
> 
> If that's the case, return -EPROBE_DEFER; we may have more luck next
> time.
> 

Fixes: 988156dc2fc9 ("drm: bridge: add it66121 driver")

> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  drivers/gpu/drm/bridge/ite-it66121.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
> index b130d01147c6..9dc41a7b9136 100644
> --- a/drivers/gpu/drm/bridge/ite-it66121.c
> +++ b/drivers/gpu/drm/bridge/ite-it66121.c
> @@ -924,6 +924,9 @@ static int it66121_probe(struct i2c_client *client,
>  	ctx->next_bridge = of_drm_find_bridge(ep);
>  	of_node_put(ep);
>  
> +	if (!ctx->next_bridge)
> +		return -EPROBE_DEFER;
> +
>  	i2c_set_clientdata(client, ctx);
>  	mutex_init(&ctx->lock);
>  
> 


Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

Thanks,
Neil

Re: [PATCH 1/2] drm/bridge: it66121: Initialize {device,vendor}_ids

[Neil Armstrong]

On 27/08/2021 18:39, Paul Cercueil wrote:
> These two arrays are populated with data read from the I2C device
> through regmap_read(), and the data is then compared with hardcoded
> vendor/product ID values of supported chips.
> 
> However, the return value of regmap_read() was never checked. This is
> fine, as long as the two arrays are zero-initialized, so that we don't
> compare the vendor/product IDs against whatever garbage is left on the
> stack.
> 
> Address this issue by zero-initializing these two arrays.
> 

Fixes: 988156dc2fc9 ("drm: bridge: add it66121 driver")

> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  drivers/gpu/drm/bridge/ite-it66121.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
> index 2f2a09adb4bc..b130d01147c6 100644
> --- a/drivers/gpu/drm/bridge/ite-it66121.c
> +++ b/drivers/gpu/drm/bridge/ite-it66121.c
> @@ -889,7 +889,7 @@ static irqreturn_t it66121_irq_threaded_handler(int irq, void *dev_id)
>  static int it66121_probe(struct i2c_client *client,
>  			 const struct i2c_device_id *id)
>  {
> -	u32 vendor_ids[2], device_ids[2], revision_id;
> +	u32 revision_id, vendor_ids[2] = { 0 }, device_ids[2] = { 0 };
>  	struct device_node *ep;
>  	int ret;
>  	struct it66121_ctx *ctx;
> 

Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

Thanks,
Neil

Re: [PATCH 1/2] drm/bridge: it66121: Initialize {device,vendor}_ids

[Robert Foss]

On Mon, 30 Aug 2021 at 11:40, Neil Armstrong <narmstrong@baylibre.com> wrote:
>
> On 27/08/2021 18:39, Paul Cercueil wrote:
> > These two arrays are populated with data read from the I2C device
> > through regmap_read(), and the data is then compared with hardcoded
> > vendor/product ID values of supported chips.
> >
> > However, the return value of regmap_read() was never checked. This is
> > fine, as long as the two arrays are zero-initialized, so that we don't
> > compare the vendor/product IDs against whatever garbage is left on the
> > stack.
> >
> > Address this issue by zero-initializing these two arrays.
> >
>
> Fixes: 988156dc2fc9 ("drm: bridge: add it66121 driver")
>
> > Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> > ---
> >  drivers/gpu/drm/bridge/ite-it66121.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
> > index 2f2a09adb4bc..b130d01147c6 100644
> > --- a/drivers/gpu/drm/bridge/ite-it66121.c
> > +++ b/drivers/gpu/drm/bridge/ite-it66121.c
> > @@ -889,7 +889,7 @@ static irqreturn_t it66121_irq_threaded_handler(int irq, void *dev_id)
> >  static int it66121_probe(struct i2c_client *client,
> >                        const struct i2c_device_id *id)
> >  {
> > -     u32 vendor_ids[2], device_ids[2], revision_id;
> > +     u32 revision_id, vendor_ids[2] = { 0 }, device_ids[2] = { 0 };
> >       struct device_node *ep;
> >       int ret;
> >       struct it66121_ctx *ctx;
> >
>
> Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

Applied series to drm-misc-next.