[PATCH] drm: Fix comment doc for format_modifiers

[PATCH] drm: Fix comment doc for format_modifiers

[Andrzej Pietrasiewicz]

To human readers

"array of struct drm_format modifiers" is almost indistinguishable from
"array of struct drm_format_modifiers", especially given that
struct drm_format_modifier does exist.

And indeed the parameter passes an array of uint64_t rather than an array
of structs, but the first words of the comment suggest that it passes
an array of structs.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
---
 drivers/gpu/drm/drm_plane.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index d6ad60ab0d38..df05d8a0dd63 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -160,7 +160,7 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane
  * @funcs: callbacks for the new plane
  * @formats: array of supported formats (DRM_FORMAT\_\*)
  * @format_count: number of elements in @formats
- * @format_modifiers: array of struct drm_format modifiers terminated by
+ * @format_modifiers: array of modifiers of struct drm_format terminated by
  *                    DRM_FORMAT_MOD_INVALID
  * @type: type of plane (overlay, primary, cursor)
  * @name: printf style format string for the plane name, or NULL for default name
-- 
2.17.1

Re: [PATCH] drm: Fix comment doc for format_modifiers

[Ville Syrjälä]

On Wed, Oct 02, 2019 at 05:43:49PM +0200, Andrzej Pietrasiewicz wrote:
> To human readers
> 
> "array of struct drm_format modifiers" is almost indistinguishable from
> "array of struct drm_format_modifiers",

Unless I'm blind those two *are* indistinguishable :P

> especially given that
> struct drm_format_modifier does exist.
> 
> And indeed the parameter passes an array of uint64_t rather than an array
> of structs, but the first words of the comment suggest that it passes
> an array of structs.
> 
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> ---
>  drivers/gpu/drm/drm_plane.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> index d6ad60ab0d38..df05d8a0dd63 100644
> --- a/drivers/gpu/drm/drm_plane.c
> +++ b/drivers/gpu/drm/drm_plane.c
> @@ -160,7 +160,7 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane

Looks like you have a broken version of git.

>   * @funcs: callbacks for the new plane
>   * @formats: array of supported formats (DRM_FORMAT\_\*)
>   * @format_count: number of elements in @formats
> - * @format_modifiers: array of struct drm_format modifiers terminated by
> + * @format_modifiers: array of modifiers of struct drm_format terminated by

Now it seems to be saying it's passing in struct drm_format foo[].
That doesn't seem right either.

>   *                    DRM_FORMAT_MOD_INVALID
>   * @type: type of plane (overlay, primary, cursor)
>   * @name: printf style format string for the plane name, or NULL for default name
> -- 
> 2.17.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Ville Syrjälä
Intel

Re: [PATCH] drm: Fix comment doc for format_modifiers

[Sam Ravnborg]

Hi Andrzej

Always good to have clear documentation.

On Wed, Oct 02, 2019 at 05:43:49PM +0200, Andrzej Pietrasiewicz wrote:
> To human readers
> 
> "array of struct drm_format modifiers" is almost indistinguishable from
> "array of struct drm_format_modifiers", especially given that
> struct drm_format_modifier does exist.
> 
> And indeed the parameter passes an array of uint64_t rather than an array
> of structs, but the first words of the comment suggest that it passes
> an array of structs.
> 
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> ---
>  drivers/gpu/drm/drm_plane.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> index d6ad60ab0d38..df05d8a0dd63 100644
> --- a/drivers/gpu/drm/drm_plane.c
> +++ b/drivers/gpu/drm/drm_plane.c
> @@ -160,7 +160,7 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane
>   * @funcs: callbacks for the new plane
>   * @formats: array of supported formats (DRM_FORMAT\_\*)
>   * @format_count: number of elements in @formats
> - * @format_modifiers: array of struct drm_format modifiers terminated by
> + * @format_modifiers: array of modifiers of struct drm_format terminated by
>   *                    DRM_FORMAT_MOD_INVALID
@format_modifiers is an array of DRM_FORMAT_* which are defined as:

#define fourcc_code(a, b, c, d) ((__u32)(a) | ((__u32)(b) << 8) | \
                                 ((__u32)(c) << 16) | ((__u32)(d) << 24))


But the array is a u64[] like this:
static const u64 tegra20_modifiers[] = {
        DRM_FORMAT_MOD_LINEAR,
        DRM_FORMAT_MOD_NVIDIA_TEGRA_TILED,
        DRM_FORMAT_MOD_INVALID
};

So this is not struct drm_format.

Can you try to give it a shot more?

	Sam

[PATCH] drm: Fix comment doc for format_modifiers

[Andrzej Pietrasiewicz]

To human readers

"array of struct drm_format modifiers" is almost indistinguishable from
"array of struct drm_format_modifiers", especially given that
struct drm_format_modifier does exist.

And indeed the parameter passes an array of uint64_t rather than an array
of structs, but the first words of the comment suggest that it passes
an array of structs.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
---
 drivers/gpu/drm/drm_plane.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index d6ad60ab0d38..0d4f9172c0dd 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -160,7 +160,7 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane
  * @funcs: callbacks for the new plane
  * @formats: array of supported formats (DRM_FORMAT\_\*)
  * @format_count: number of elements in @formats
- * @format_modifiers: array of struct drm_format modifiers terminated by
+ * @format_modifiers: array of format modifiers terminated by
  *                    DRM_FORMAT_MOD_INVALID
  * @type: type of plane (overlay, primary, cursor)
  * @name: printf style format string for the plane name, or NULL for default name
-- 
2.17.1

Re: [PATCH] drm: Fix comment doc for format_modifiers

[Ville Syrjälä]

On Thu, Oct 03, 2019 at 09:51:18AM +0200, Andrzej Pietrasiewicz wrote:
> To human readers

The commit message is always for human readers, no need to point that
out...

> 
> "array of struct drm_format modifiers" is almost indistinguishable from
> "array of struct drm_format_modifiers", especially given that
> struct drm_format_modifier does exist.

..but this paragraph still manages to 100% confuse this particular human.

The actual code changes lgtm, so with the commit message reworded
this patch is
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> 
> And indeed the parameter passes an array of uint64_t rather than an array
> of structs, but the first words of the comment suggest that it passes
> 
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> ---
>  drivers/gpu/drm/drm_plane.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> index d6ad60ab0d38..0d4f9172c0dd 100644
> --- a/drivers/gpu/drm/drm_plane.c
> +++ b/drivers/gpu/drm/drm_plane.c
> @@ -160,7 +160,7 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane
>   * @funcs: callbacks for the new plane
>   * @formats: array of supported formats (DRM_FORMAT\_\*)
>   * @format_count: number of elements in @formats
> - * @format_modifiers: array of struct drm_format modifiers terminated by
> + * @format_modifiers: array of format modifiers terminated by
>   *                    DRM_FORMAT_MOD_INVALID
>   * @type: type of plane (overlay, primary, cursor)
>   * @name: printf style format string for the plane name, or NULL for default name
> -- 
> 2.17.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Ville Syrjälä
Intel

Re: [PATCH] drm: Fix comment doc for format_modifiers

[Eric Engestrom]

On Thursday, 2019-10-03 16:53:18 +0300, Ville Syrjälä wrote:
> On Thu, Oct 03, 2019 at 09:51:18AM +0200, Andrzej Pietrasiewicz wrote:
> > To human readers
> 
> The commit message is always for human readers, no need to point that
> out...
> 
> > 
> > "array of struct drm_format modifiers" is almost indistinguishable from
> > "array of struct drm_format_modifiers", especially given that
> > struct drm_format_modifier does exist.
> 
> ..but this paragraph still manages to 100% confuse this particular human.

There's an underscore instead of a space on the second line
(s/drm_format modifiers/drm_format_modifiers/).

It should definitely be reworded to be much clearer.

> 
> The actual code changes lgtm, so with the commit message reworded
> this patch is
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> > 
> > And indeed the parameter passes an array of uint64_t rather than an array
> > of structs, but the first words of the comment suggest that it passes
> > 
> > Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> > ---
> >  drivers/gpu/drm/drm_plane.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> > index d6ad60ab0d38..0d4f9172c0dd 100644
> > --- a/drivers/gpu/drm/drm_plane.c
> > +++ b/drivers/gpu/drm/drm_plane.c
> > @@ -160,7 +160,7 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane
> >   * @funcs: callbacks for the new plane
> >   * @formats: array of supported formats (DRM_FORMAT\_\*)
> >   * @format_count: number of elements in @formats
> > - * @format_modifiers: array of struct drm_format modifiers terminated by
> > + * @format_modifiers: array of format modifiers terminated by
> >   *                    DRM_FORMAT_MOD_INVALID
> >   * @type: type of plane (overlay, primary, cursor)
> >   * @name: printf style format string for the plane name, or NULL for default name
> > -- 
> > 2.17.1
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 

Re: [PATCH] drm: Fix comment doc for format_modifiers

[Ville Syrjälä]

On Fri, Oct 04, 2019 at 08:08:26PM +0100, Eric Engestrom wrote:
> On Thursday, 2019-10-03 16:53:18 +0300, Ville Syrjälä wrote:
> > On Thu, Oct 03, 2019 at 09:51:18AM +0200, Andrzej Pietrasiewicz wrote:
> > > To human readers
> > 
> > The commit message is always for human readers, no need to point that
> > out...
> > 
> > > 
> > > "array of struct drm_format modifiers" is almost indistinguishable from
> > > "array of struct drm_format_modifiers", especially given that
> > > struct drm_format_modifier does exist.
> > 
> > ..but this paragraph still manages to 100% confuse this particular human.
> 
> There's an underscore instead of a space on the second line
> (s/drm_format modifiers/drm_format_modifiers/).

OK, so I guess I really am blind.

> 
> It should definitely be reworded to be much clearer.
> 
> > 
> > The actual code changes lgtm, so with the commit message reworded
> > this patch is
> > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > > 
> > > And indeed the parameter passes an array of uint64_t rather than an array
> > > of structs, but the first words of the comment suggest that it passes
> > > 
> > > Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> > > ---
> > >  drivers/gpu/drm/drm_plane.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> > > index d6ad60ab0d38..0d4f9172c0dd 100644
> > > --- a/drivers/gpu/drm/drm_plane.c
> > > +++ b/drivers/gpu/drm/drm_plane.c
> > > @@ -160,7 +160,7 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane
> > >   * @funcs: callbacks for the new plane
> > >   * @formats: array of supported formats (DRM_FORMAT\_\*)
> > >   * @format_count: number of elements in @formats
> > > - * @format_modifiers: array of struct drm_format modifiers terminated by
> > > + * @format_modifiers: array of format modifiers terminated by
> > >   *                    DRM_FORMAT_MOD_INVALID
> > >   * @type: type of plane (overlay, primary, cursor)
> > >   * @name: printf style format string for the plane name, or NULL for default name
> > > -- 
> > > 2.17.1
> > > 
> > > _______________________________________________
> > > dri-devel mailing list
> > > dri-devel@lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > 

-- 
Ville Syrjälä
Intel

[PATCH] drm: Fix comment doc for format_modifiers

[Andrzej Pietrasiewicz]

The parameter passes an array of uint64_t rather than an array
of structs, but the first words of the comment suggest that it passes
an array of structs - if the reader stops reading at the word "struct".

If the commit is read beyond that point the reader will likely confuse
"drm_format<SPACE>modifiers" with "drm_format<UNDERSCORE>modifiers" and
understand the meaning as "passing an array of elements which are of type
struct drm_format_modifier". That is not correct.

Only if the reader is able to read the comment as
"array of struct drm_format<SPACE>modifiers" will they be close to the
correct meaning. But still not quite there, because the modifiers do not
influence struct drm_format in any way - it is not clear what "a modifier
of a struct" would be.

The comment is changed to simply say that the parameter passes an array of
format modifiers, which is the correct meaning.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/drm_plane.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index d6ad60ab0d38..0d4f9172c0dd 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -160,7 +160,7 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane
  * @funcs: callbacks for the new plane
  * @formats: array of supported formats (DRM_FORMAT\_\*)
  * @format_count: number of elements in @formats
- * @format_modifiers: array of struct drm_format modifiers terminated by
+ * @format_modifiers: array of format modifiers terminated by
  *                    DRM_FORMAT_MOD_INVALID
  * @type: type of plane (overlay, primary, cursor)
  * @name: printf style format string for the plane name, or NULL for default name
-- 
2.17.1