diff mbox series

[1/2] drm/probe-helper: Add helper for drm_helper_probe_single_connector_modes()

Message ID 20220426114627.1.I2dd93486c6952bd52f2020904de0133970d11b29@changeid (mailing list archive)
State New, archived
Headers show
Series [1/2] drm/probe-helper: Add helper for drm_helper_probe_single_connector_modes() | expand

Commit Message

Doug Anderson April 26, 2022, 6:46 p.m. UTC
The drm_helper_probe_single_connector_modes() is a bit long. Let's
break a chunk off to update and validate modes. This helps avoid one
goto and also will allow us to more easily call the helper a second
time in a future patch without adding looping or another goto.

This change is intended to be a no-op change--just code movement.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 drivers/gpu/drm/drm_probe_helper.c | 105 ++++++++++++++++-------------
 1 file changed, 59 insertions(+), 46 deletions(-)

Comments

Abhinav Kumar April 26, 2022, 10:21 p.m. UTC | #1
On 4/26/2022 11:46 AM, Douglas Anderson wrote:
> The drm_helper_probe_single_connector_modes() is a bit long. Let's
> break a chunk off to update and validate modes. This helps avoid one
> goto and also will allow us to more easily call the helper a second
> time in a future patch without adding looping or another goto.
> 
> This change is intended to be a no-op change--just code movement.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

I think this cleanup looks reasonable to me.

Hence,

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
> ---
> 
>   drivers/gpu/drm/drm_probe_helper.c | 105 ++++++++++++++++-------------
>   1 file changed, 59 insertions(+), 46 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index 682359512996..819225629010 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -354,6 +354,61 @@ drm_helper_probe_detect(struct drm_connector *connector,
>   }
>   EXPORT_SYMBOL(drm_helper_probe_detect);
>   
> +static bool _drm_helper_update_and_validate(struct drm_connector *connector,
> +					    uint32_t maxX, uint32_t maxY,
> +					    struct drm_modeset_acquire_ctx *ctx)
> +{
> +	struct drm_device *dev = connector->dev;
> +	struct drm_display_mode *mode;
> +	int mode_flags = 0;
> +	int ret;
> +
> +	drm_connector_list_update(connector);
> +
> +	if (connector->interlace_allowed)
> +		mode_flags |= DRM_MODE_FLAG_INTERLACE;
> +	if (connector->doublescan_allowed)
> +		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
> +	if (connector->stereo_allowed)
> +		mode_flags |= DRM_MODE_FLAG_3D_MASK;
> +
> +	list_for_each_entry(mode, &connector->modes, head) {
> +		if (mode->status != MODE_OK)
> +			continue;
> +
> +		mode->status = drm_mode_validate_driver(dev, mode);
> +		if (mode->status != MODE_OK)
> +			continue;
> +
> +		mode->status = drm_mode_validate_size(mode, maxX, maxY);
> +		if (mode->status != MODE_OK)
> +			continue;
> +
> +		mode->status = drm_mode_validate_flag(mode, mode_flags);
> +		if (mode->status != MODE_OK)
> +			continue;
> +
> +		ret = drm_mode_validate_pipeline(mode, connector, ctx,
> +						 &mode->status);
> +		if (ret) {
> +			drm_dbg_kms(dev,
> +				    "drm_mode_validate_pipeline failed: %d\n",
> +				    ret);
> +
> +			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK))
> +				mode->status = MODE_ERROR;
> +			else
> +				return true;
> +		}
> +
> +		if (mode->status != MODE_OK)
> +			continue;
> +		mode->status = drm_mode_validate_ycbcr420(mode, connector);
> +	}
> +
> +	return false;
> +}
> +
>   /**
>    * drm_helper_probe_single_connector_modes - get complete set of display modes
>    * @connector: connector to probe
> @@ -421,7 +476,6 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
>   	const struct drm_connector_helper_funcs *connector_funcs =
>   		connector->helper_private;
>   	int count = 0, ret;
> -	int mode_flags = 0;
>   	bool verbose_prune = true;
>   	enum drm_connector_status old_status;
>   	struct drm_modeset_acquire_ctx ctx;
> @@ -519,52 +573,11 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
>   			   connector->status == connector_status_unknown))
>   		count = drm_add_modes_noedid(connector, 1024, 768);
>   	count += drm_helper_probe_add_cmdline_mode(connector);
> -	if (count == 0)
> -		goto prune;
> -
> -	drm_connector_list_update(connector);
> -
> -	if (connector->interlace_allowed)
> -		mode_flags |= DRM_MODE_FLAG_INTERLACE;
> -	if (connector->doublescan_allowed)
> -		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
> -	if (connector->stereo_allowed)
> -		mode_flags |= DRM_MODE_FLAG_3D_MASK;
> -
> -	list_for_each_entry(mode, &connector->modes, head) {
> -		if (mode->status != MODE_OK)
> -			continue;
> -
> -		mode->status = drm_mode_validate_driver(dev, mode);
> -		if (mode->status != MODE_OK)
> -			continue;
> -
> -		mode->status = drm_mode_validate_size(mode, maxX, maxY);
> -		if (mode->status != MODE_OK)
> -			continue;
> -
> -		mode->status = drm_mode_validate_flag(mode, mode_flags);
> -		if (mode->status != MODE_OK)
> -			continue;
> -
> -		ret = drm_mode_validate_pipeline(mode, connector, &ctx,
> -						 &mode->status);
> -		if (ret) {
> -			drm_dbg_kms(dev,
> -				    "drm_mode_validate_pipeline failed: %d\n",
> -				    ret);
> -
> -			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK)) {
> -				mode->status = MODE_ERROR;
> -			} else {
> -				drm_modeset_backoff(&ctx);
> -				goto retry;
> -			}
> +	if (count != 0) {
> +		if (_drm_helper_update_and_validate(connector, maxX, maxY, &ctx)) {
> +			drm_modeset_backoff(&ctx);
> +			goto retry;
>   		}
> -
> -		if (mode->status != MODE_OK)
> -			continue;
> -		mode->status = drm_mode_validate_ycbcr420(mode, connector);
>   	}
>   
>   prune:
Thomas Zimmermann May 5, 2022, 6:34 p.m. UTC | #2
Hi

Am 26.04.22 um 20:46 schrieb Douglas Anderson:
> The drm_helper_probe_single_connector_modes() is a bit long. Let's
> break a chunk off to update and validate modes. This helps avoid one
> goto and also will allow us to more easily call the helper a second
> time in a future patch without adding looping or another goto.
> 
> This change is intended to be a no-op change--just code movement.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>


> ---
> 
>   drivers/gpu/drm/drm_probe_helper.c | 105 ++++++++++++++++-------------
>   1 file changed, 59 insertions(+), 46 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index 682359512996..819225629010 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -354,6 +354,61 @@ drm_helper_probe_detect(struct drm_connector *connector,
>   }
>   EXPORT_SYMBOL(drm_helper_probe_detect);
>   
> +static bool _drm_helper_update_and_validate(struct drm_connector *connector,

AFAIK convention is to use two underscores for internal names.

> +					    uint32_t maxX, uint32_t maxY,
> +					    struct drm_modeset_acquire_ctx *ctx)
> +{
> +	struct drm_device *dev = connector->dev;
> +	struct drm_display_mode *mode;
> +	int mode_flags = 0;
> +	int ret;
> +
> +	drm_connector_list_update(connector);
> +
> +	if (connector->interlace_allowed)
> +		mode_flags |= DRM_MODE_FLAG_INTERLACE;
> +	if (connector->doublescan_allowed)
> +		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
> +	if (connector->stereo_allowed)
> +		mode_flags |= DRM_MODE_FLAG_3D_MASK;
> +
> +	list_for_each_entry(mode, &connector->modes, head) {
> +		if (mode->status != MODE_OK)
> +			continue;
> +
> +		mode->status = drm_mode_validate_driver(dev, mode);
> +		if (mode->status != MODE_OK)
> +			continue;
> +
> +		mode->status = drm_mode_validate_size(mode, maxX, maxY);
> +		if (mode->status != MODE_OK)
> +			continue;
> +
> +		mode->status = drm_mode_validate_flag(mode, mode_flags);
> +		if (mode->status != MODE_OK)
> +			continue;
> +
> +		ret = drm_mode_validate_pipeline(mode, connector, ctx,
> +						 &mode->status);
> +		if (ret) {
> +			drm_dbg_kms(dev,
> +				    "drm_mode_validate_pipeline failed: %d\n",
> +				    ret);
> +
> +			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK))
> +				mode->status = MODE_ERROR;
> +			else
> +				return true;

Returning true is non-intuitive. It looks as if we report success when 
it actually signals a retry.

I suggest to return 'ret' here and let the caller decide. On success at 
the end of the function, it would return 0 as usual.

Best regards
Thomas

> +		}
> +
> +		if (mode->status != MODE_OK)
> +			continue;
> +		mode->status = drm_mode_validate_ycbcr420(mode, connector);
> +	}
> +
> +	return false;
> +}
> +
>   /**
>    * drm_helper_probe_single_connector_modes - get complete set of display modes
>    * @connector: connector to probe
> @@ -421,7 +476,6 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
>   	const struct drm_connector_helper_funcs *connector_funcs =
>   		connector->helper_private;
>   	int count = 0, ret;
> -	int mode_flags = 0;
>   	bool verbose_prune = true;
>   	enum drm_connector_status old_status;
>   	struct drm_modeset_acquire_ctx ctx;
> @@ -519,52 +573,11 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
>   			   connector->status == connector_status_unknown))
>   		count = drm_add_modes_noedid(connector, 1024, 768);
>   	count += drm_helper_probe_add_cmdline_mode(connector);
> -	if (count == 0)
> -		goto prune;
> -
> -	drm_connector_list_update(connector);
> -
> -	if (connector->interlace_allowed)
> -		mode_flags |= DRM_MODE_FLAG_INTERLACE;
> -	if (connector->doublescan_allowed)
> -		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
> -	if (connector->stereo_allowed)
> -		mode_flags |= DRM_MODE_FLAG_3D_MASK;
> -
> -	list_for_each_entry(mode, &connector->modes, head) {
> -		if (mode->status != MODE_OK)
> -			continue;
> -
> -		mode->status = drm_mode_validate_driver(dev, mode);
> -		if (mode->status != MODE_OK)
> -			continue;
> -
> -		mode->status = drm_mode_validate_size(mode, maxX, maxY);
> -		if (mode->status != MODE_OK)
> -			continue;
> -
> -		mode->status = drm_mode_validate_flag(mode, mode_flags);
> -		if (mode->status != MODE_OK)
> -			continue;
> -
> -		ret = drm_mode_validate_pipeline(mode, connector, &ctx,
> -						 &mode->status);
> -		if (ret) {
> -			drm_dbg_kms(dev,
> -				    "drm_mode_validate_pipeline failed: %d\n",
> -				    ret);
> -
> -			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK)) {
> -				mode->status = MODE_ERROR;
> -			} else {
> -				drm_modeset_backoff(&ctx);
> -				goto retry;
> -			}
> +	if (count != 0) {
> +		if (_drm_helper_update_and_validate(connector, maxX, maxY, &ctx)) {
> +			drm_modeset_backoff(&ctx);
> +			goto retry;
>   		}
> -
> -		if (mode->status != MODE_OK)
> -			continue;
> -		mode->status = drm_mode_validate_ycbcr420(mode, connector);
>   	}
>   
>   prune:
Doug Anderson May 5, 2022, 7:46 p.m. UTC | #3
Hi,

On Thu, May 5, 2022 at 11:34 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>
> Hi
>
> Am 26.04.22 um 20:46 schrieb Douglas Anderson:
> > The drm_helper_probe_single_connector_modes() is a bit long. Let's
> > break a chunk off to update and validate modes. This helps avoid one
> > goto and also will allow us to more easily call the helper a second
> > time in a future patch without adding looping or another goto.
> >
> > This change is intended to be a no-op change--just code movement.
> >
> > Signed-off-by: Douglas Anderson <dianders@chromium.org>
>
>
> > ---
> >
> >   drivers/gpu/drm/drm_probe_helper.c | 105 ++++++++++++++++-------------
> >   1 file changed, 59 insertions(+), 46 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> > index 682359512996..819225629010 100644
> > --- a/drivers/gpu/drm/drm_probe_helper.c
> > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > @@ -354,6 +354,61 @@ drm_helper_probe_detect(struct drm_connector *connector,
> >   }
> >   EXPORT_SYMBOL(drm_helper_probe_detect);
> >
> > +static bool _drm_helper_update_and_validate(struct drm_connector *connector,
>
> AFAIK convention is to use two underscores for internal names.

Sure! I'll spin with this.


> > +                                         uint32_t maxX, uint32_t maxY,
> > +                                         struct drm_modeset_acquire_ctx *ctx)
> > +{
> > +     struct drm_device *dev = connector->dev;
> > +     struct drm_display_mode *mode;
> > +     int mode_flags = 0;
> > +     int ret;
> > +
> > +     drm_connector_list_update(connector);
> > +
> > +     if (connector->interlace_allowed)
> > +             mode_flags |= DRM_MODE_FLAG_INTERLACE;
> > +     if (connector->doublescan_allowed)
> > +             mode_flags |= DRM_MODE_FLAG_DBLSCAN;
> > +     if (connector->stereo_allowed)
> > +             mode_flags |= DRM_MODE_FLAG_3D_MASK;
> > +
> > +     list_for_each_entry(mode, &connector->modes, head) {
> > +             if (mode->status != MODE_OK)
> > +                     continue;
> > +
> > +             mode->status = drm_mode_validate_driver(dev, mode);
> > +             if (mode->status != MODE_OK)
> > +                     continue;
> > +
> > +             mode->status = drm_mode_validate_size(mode, maxX, maxY);
> > +             if (mode->status != MODE_OK)
> > +                     continue;
> > +
> > +             mode->status = drm_mode_validate_flag(mode, mode_flags);
> > +             if (mode->status != MODE_OK)
> > +                     continue;
> > +
> > +             ret = drm_mode_validate_pipeline(mode, connector, ctx,
> > +                                              &mode->status);
> > +             if (ret) {
> > +                     drm_dbg_kms(dev,
> > +                                 "drm_mode_validate_pipeline failed: %d\n",
> > +                                 ret);
> > +
> > +                     if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK))
> > +                             mode->status = MODE_ERROR;
> > +                     else
> > +                             return true;
>
> Returning true is non-intuitive. It looks as if we report success when
> it actually signals a retry.
>
> I suggest to return 'ret' here and let the caller decide. On success at
> the end of the function, it would return 0 as usual.

There's a madness to my method. I originally had it returning "ret"
but then I felt like the callers now needed to handle three cases:

a) ret = -EDEADLK
b) ret = 0
c) ret = some other error

In reality _drm_helper_update_and_validate() never returned anything
other than a) or b), so adding the extra error handling for c) seemed
like a waste. ...but it also felt like if it violated the abstraction
of _drm_helper_update_and_validate() returning an error code if I
didn't handle c).

In any case, I'll change it back to an error code. Maybe a compromise would be:

ret = _drm_helper_update_and_validate(...)
if (ret == -EDEADLK) {
  drm_modeset_backoff(...)
  goto retry;
}
WARN_ON(ret);

...so we at least document that ret can only be one of the two values
and we'll get a warning splat if it ever happens, but we don't need to
add complex error handling for a case that the code can't hit. Ah,
looking above I guess that matches what the function does earlier too.

OK, I'll give a few more days for feedback on this series and I'll
spin with the two changes you've requested.

-Doug

-Doug
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 682359512996..819225629010 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -354,6 +354,61 @@  drm_helper_probe_detect(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_helper_probe_detect);
 
+static bool _drm_helper_update_and_validate(struct drm_connector *connector,
+					    uint32_t maxX, uint32_t maxY,
+					    struct drm_modeset_acquire_ctx *ctx)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_display_mode *mode;
+	int mode_flags = 0;
+	int ret;
+
+	drm_connector_list_update(connector);
+
+	if (connector->interlace_allowed)
+		mode_flags |= DRM_MODE_FLAG_INTERLACE;
+	if (connector->doublescan_allowed)
+		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
+	if (connector->stereo_allowed)
+		mode_flags |= DRM_MODE_FLAG_3D_MASK;
+
+	list_for_each_entry(mode, &connector->modes, head) {
+		if (mode->status != MODE_OK)
+			continue;
+
+		mode->status = drm_mode_validate_driver(dev, mode);
+		if (mode->status != MODE_OK)
+			continue;
+
+		mode->status = drm_mode_validate_size(mode, maxX, maxY);
+		if (mode->status != MODE_OK)
+			continue;
+
+		mode->status = drm_mode_validate_flag(mode, mode_flags);
+		if (mode->status != MODE_OK)
+			continue;
+
+		ret = drm_mode_validate_pipeline(mode, connector, ctx,
+						 &mode->status);
+		if (ret) {
+			drm_dbg_kms(dev,
+				    "drm_mode_validate_pipeline failed: %d\n",
+				    ret);
+
+			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK))
+				mode->status = MODE_ERROR;
+			else
+				return true;
+		}
+
+		if (mode->status != MODE_OK)
+			continue;
+		mode->status = drm_mode_validate_ycbcr420(mode, connector);
+	}
+
+	return false;
+}
+
 /**
  * drm_helper_probe_single_connector_modes - get complete set of display modes
  * @connector: connector to probe
@@ -421,7 +476,6 @@  int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 	const struct drm_connector_helper_funcs *connector_funcs =
 		connector->helper_private;
 	int count = 0, ret;
-	int mode_flags = 0;
 	bool verbose_prune = true;
 	enum drm_connector_status old_status;
 	struct drm_modeset_acquire_ctx ctx;
@@ -519,52 +573,11 @@  int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 			   connector->status == connector_status_unknown))
 		count = drm_add_modes_noedid(connector, 1024, 768);
 	count += drm_helper_probe_add_cmdline_mode(connector);
-	if (count == 0)
-		goto prune;
-
-	drm_connector_list_update(connector);
-
-	if (connector->interlace_allowed)
-		mode_flags |= DRM_MODE_FLAG_INTERLACE;
-	if (connector->doublescan_allowed)
-		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
-	if (connector->stereo_allowed)
-		mode_flags |= DRM_MODE_FLAG_3D_MASK;
-
-	list_for_each_entry(mode, &connector->modes, head) {
-		if (mode->status != MODE_OK)
-			continue;
-
-		mode->status = drm_mode_validate_driver(dev, mode);
-		if (mode->status != MODE_OK)
-			continue;
-
-		mode->status = drm_mode_validate_size(mode, maxX, maxY);
-		if (mode->status != MODE_OK)
-			continue;
-
-		mode->status = drm_mode_validate_flag(mode, mode_flags);
-		if (mode->status != MODE_OK)
-			continue;
-
-		ret = drm_mode_validate_pipeline(mode, connector, &ctx,
-						 &mode->status);
-		if (ret) {
-			drm_dbg_kms(dev,
-				    "drm_mode_validate_pipeline failed: %d\n",
-				    ret);
-
-			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK)) {
-				mode->status = MODE_ERROR;
-			} else {
-				drm_modeset_backoff(&ctx);
-				goto retry;
-			}
+	if (count != 0) {
+		if (_drm_helper_update_and_validate(connector, maxX, maxY, &ctx)) {
+			drm_modeset_backoff(&ctx);
+			goto retry;
 		}
-
-		if (mode->status != MODE_OK)
-			continue;
-		mode->status = drm_mode_validate_ycbcr420(mode, connector);
 	}
 
 prune: