[PATCH 0/3] drm/tinydrm: Fix compiler warnings

[PATCH 0/3] drm/tinydrm: Fix compiler warnings

[Noralf Trønnes]

Dave pulled tinydrm yesterday which triggered some compiler warnings:

Dave Airlie:
drivers/gpu/drm/tinydrm/mipi-dbi.c: In function ‘mipi_dbi_debugfs_command_write’:
drivers/gpu/drm/tinydrm/mipi-dbi.c:905:8: warning: ‘cmd’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  ret = mipi_dbi_command_buf(mipi, cmd, parameters, i);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I didn't see this on gcc 4.8, but it showed up when I used gcc 6.2.

kbuild test robot:
[drm:drm-next 1199/1208] drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c:198:26: error: redefinition of 'tinydrm_of_find_backlight'

kbuild test robot:
   drivers/gpu/drm/tinydrm/mipi-dbi.c: In function 'mipi_dbi_typec1_command':
>> drivers/gpu/drm/tinydrm/mipi-dbi.c:65:20: warning: field width specifier '*' expects argument of type 'int', but argument 5 has type 'size_t {aka long unsigned int}' [-Wformat=]
      DRM_DEBUG_DRIVER("cmd=%02x, par=%*ph\n", cmd, len, data); \
                       ^
   include/drm/drmP.h:228:40: note: in definition of macro 'DRM_DEBUG_DRIVER'
     drm_printk(KERN_DEBUG, DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
                                           ^~~
>> drivers/gpu/drm/tinydrm/mipi-dbi.c:671:2: note: in expansion of macro 'MIPI_DBI_DEBUG_COMMAND'
     MIPI_DBI_DEBUG_COMMAND(cmd, parameters, num);
     ^~~~~~~~~~~~~~~~~~~~~~

Noralf.


Noralf Trønnes (3):
  drm/tinydrm: mipi-dbi: Silence: ‘cmd’ may be used uninitialized
  drm/tinydrm: mipi-dbi: Fix field width specifier warning
  drm/tinydrm: helpers: Properly fix backlight dependency

 drivers/gpu/drm/tinydrm/mipi-dbi.c    |  6 +++---
 include/drm/tinydrm/tinydrm-helpers.h | 19 -------------------
 2 files changed, 3 insertions(+), 22 deletions(-)

--
2.10.2

[PATCH 1/3] drm/tinydrm: mipi-dbi: Silence: ‘cmd’ may be used uninitialized

[Noralf Trønnes]

Fix this warning:
drivers/gpu/drm/tinydrm/mipi-dbi.c: In function ‘mipi_dbi_debugfs_command_write’:
drivers/gpu/drm/tinydrm/mipi-dbi.c:905:8: warning: ‘cmd’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  ret = mipi_dbi_command_buf(mipi, cmd, parameters, i);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

cmd can't be used uninitialized, but to satisfy the compiler,
initialize it to zero.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/tinydrm/mipi-dbi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c
index 07d49ba..2caecde 100644
--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -863,7 +863,7 @@ static ssize_t mipi_dbi_debugfs_command_write(struct file *file,
 {
 	struct seq_file *m = file->private_data;
 	struct mipi_dbi *mipi = m->private;
-	u8 val, cmd, parameters[64];
+	u8 val, cmd = 0, parameters[64];
 	char *buf, *pos, *token;
 	unsigned int i;
 	int ret;
-- 
2.10.2

[PATCH 2/3] drm/tinydrm: mipi-dbi: Fix field width specifier warning

[Noralf Trønnes]

This warning is seen on 64-bit builds in functions:
   'mipi_dbi_typec1_command':
   'mipi_dbi_typec3_command_read':
   'mipi_dbi_typec3_command':

>> drivers/gpu/drm/tinydrm/mipi-dbi.c:65:20: warning: field width specifier '*' expects argument of type 'int', but argument 5 has type 'size_t {aka long unsigned int}' [-Wformat=]
      DRM_DEBUG_DRIVER("cmd=%02x, par=%*ph\n", cmd, len, data); \
                       ^
   include/drm/drmP.h:228:40: note: in definition of macro 'DRM_DEBUG_DRIVER'
     drm_printk(KERN_DEBUG, DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
                                           ^~~
>> drivers/gpu/drm/tinydrm/mipi-dbi.c:671:2: note: in expansion of macro 'MIPI_DBI_DEBUG_COMMAND'
     MIPI_DBI_DEBUG_COMMAND(cmd, parameters, num);
     ^~~~~~~~~~~~~~~~~~~~~~

Fix by casting 'len' to int in the macro MIPI_DBI_DEBUG_COMMAND().
There is no chance of overflow.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/tinydrm/mipi-dbi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c
index 2caecde..2d21b49 100644
--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -62,9 +62,9 @@
 	if (!len) \
 		DRM_DEBUG_DRIVER("cmd=%02x\n", cmd); \
 	else if (len <= 32) \
-		DRM_DEBUG_DRIVER("cmd=%02x, par=%*ph\n", cmd, len, data); \
+		DRM_DEBUG_DRIVER("cmd=%02x, par=%*ph\n", cmd, (int)len, data);\
 	else \
-		DRM_DEBUG_DRIVER("cmd=%02x, len=%zu\n", cmd, len); \
+		DRM_DEBUG_DRIVER("cmd=%02x, len=%zu\n", cmd, (int)len); \
 })
 
 static const u8 mipi_dbi_dcs_read_commands[] = {
-- 
2.10.2

[PATCH 3/3] drm/tinydrm: helpers: Properly fix backlight dependency

[Noralf Trønnes]

BACKLIGHT_CLASS_DEVICE was selected in the last version of the
tinydrm patchset to fix the backlight dependency, but the
ifdef CONFIG_BACKLIGHT_CLASS_DEVICE was forgotten. Fix that.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 include/drm/tinydrm/tinydrm-helpers.h | 19 -------------------
 1 file changed, 19 deletions(-)

diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
index 78175fe..9b9b6cf 100644
--- a/include/drm/tinydrm/tinydrm-helpers.h
+++ b/include/drm/tinydrm/tinydrm-helpers.h
@@ -44,28 +44,9 @@ void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
 				struct drm_framebuffer *fb,
 				struct drm_clip_rect *clip, bool swap);
 
-#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
 struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
 int tinydrm_enable_backlight(struct backlight_device *backlight);
 int tinydrm_disable_backlight(struct backlight_device *backlight);
-#else
-static inline struct backlight_device *
-tinydrm_of_find_backlight(struct device *dev)
-{
-	return NULL;
-}
-
-static inline int tinydrm_enable_backlight(struct backlight_device *backlight)
-{
-	return 0;
-}
-
-static inline int
-tinydrm_disable_backlight(struct backlight_device *backlight)
-{
-	return 0;
-}
-#endif
 
 size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len);
 bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw);
-- 
2.10.2

Re: [PATCH 0/3] drm/tinydrm: Fix compiler warnings

[Noralf Trønnes]

I see that I forgot cc'ing Dave Airlie on this, and I just realised
that the backlight problem isn't just a warning, but it actually causes
a build failure if backlight is built as a module.
I missed this in my hurry to get this out the door, sorry.


Den 23.02.2017 14.29, skrev Noralf Trønnes:
> Dave pulled tinydrm yesterday which triggered some compiler warnings:
>
> Dave Airlie:
> drivers/gpu/drm/tinydrm/mipi-dbi.c: In function ‘mipi_dbi_debugfs_command_write’:
> drivers/gpu/drm/tinydrm/mipi-dbi.c:905:8: warning: ‘cmd’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>    ret = mipi_dbi_command_buf(mipi, cmd, parameters, i);
>          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> I didn't see this on gcc 4.8, but it showed up when I used gcc 6.2.
>
> kbuild test robot:
> [drm:drm-next 1199/1208] drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c:198:26: error: redefinition of 'tinydrm_of_find_backlight'
>
> kbuild test robot:
>     drivers/gpu/drm/tinydrm/mipi-dbi.c: In function 'mipi_dbi_typec1_command':
>>> drivers/gpu/drm/tinydrm/mipi-dbi.c:65:20: warning: field width specifier '*' expects argument of type 'int', but argument 5 has type 'size_t {aka long unsigned int}' [-Wformat=]
>        DRM_DEBUG_DRIVER("cmd=%02x, par=%*ph\n", cmd, len, data); \
>                         ^
>     include/drm/drmP.h:228:40: note: in definition of macro 'DRM_DEBUG_DRIVER'
>       drm_printk(KERN_DEBUG, DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
>                                             ^~~
>>> drivers/gpu/drm/tinydrm/mipi-dbi.c:671:2: note: in expansion of macro 'MIPI_DBI_DEBUG_COMMAND'
>       MIPI_DBI_DEBUG_COMMAND(cmd, parameters, num);
>       ^~~~~~~~~~~~~~~~~~~~~~
>
> Noralf.
>
>
> Noralf Trønnes (3):
>    drm/tinydrm: mipi-dbi: Silence: ‘cmd’ may be used uninitialized
>    drm/tinydrm: mipi-dbi: Fix field width specifier warning
>    drm/tinydrm: helpers: Properly fix backlight dependency
>
>   drivers/gpu/drm/tinydrm/mipi-dbi.c    |  6 +++---
>   include/drm/tinydrm/tinydrm-helpers.h | 19 -------------------
>   2 files changed, 3 insertions(+), 22 deletions(-)
>
> --
> 2.10.2
>

Re: [PATCH 3/3] drm/tinydrm: helpers: Properly fix backlight dependency

[Noralf Trønnes]

Den 23.02.2017 14.29, skrev Noralf Trønnes:
> BACKLIGHT_CLASS_DEVICE was selected in the last version of the
> tinydrm patchset to fix the backlight dependency, but the
> ifdef CONFIG_BACKLIGHT_CLASS_DEVICE was forgotten. Fix that.
>
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---

Please apply this, it causes a build error if backlight is built as
a module. In my haste to fix the problems reported after tinydrm was
pulled, I mistook it for a warning so it was mislabeled.
Sorry about the noise caused by tinydrm.

Noralf.


>   include/drm/tinydrm/tinydrm-helpers.h | 19 -------------------
>   1 file changed, 19 deletions(-)
>
> diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
> index 78175fe..9b9b6cf 100644
> --- a/include/drm/tinydrm/tinydrm-helpers.h
> +++ b/include/drm/tinydrm/tinydrm-helpers.h
> @@ -44,28 +44,9 @@ void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
>   				struct drm_framebuffer *fb,
>   				struct drm_clip_rect *clip, bool swap);
>   
> -#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
>   struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
>   int tinydrm_enable_backlight(struct backlight_device *backlight);
>   int tinydrm_disable_backlight(struct backlight_device *backlight);
> -#else
> -static inline struct backlight_device *
> -tinydrm_of_find_backlight(struct device *dev)
> -{
> -	return NULL;
> -}
> -
> -static inline int tinydrm_enable_backlight(struct backlight_device *backlight)
> -{
> -	return 0;
> -}
> -
> -static inline int
> -tinydrm_disable_backlight(struct backlight_device *backlight)
> -{
> -	return 0;
> -}
> -#endif
>   
>   size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len);
>   bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw);

Re: [PATCH 3/3] drm/tinydrm: helpers: Properly fix backlight dependency

[Daniel Vetter]

On Sun, Feb 26, 2017 at 11:44:40PM +0100, Noralf Trønnes wrote:
> 
> Den 23.02.2017 14.29, skrev Noralf Trønnes:
> > BACKLIGHT_CLASS_DEVICE was selected in the last version of the
> > tinydrm patchset to fix the backlight dependency, but the
> > ifdef CONFIG_BACKLIGHT_CLASS_DEVICE was forgotten. Fix that.
> > 
> > Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> > ---
> 
> Please apply this, it causes a build error if backlight is built as
> a module. In my haste to fix the problems reported after tinydrm was
> pulled, I mistook it for a warning so it was mislabeled.
> Sorry about the noise caused by tinydrm.

They are all already applied and in Linus' tree. Dave Airlie generally
doesn't send out a mail when he merges stuff.
-Daniel

> 
> Noralf.
> 
> 
> >   include/drm/tinydrm/tinydrm-helpers.h | 19 -------------------
> >   1 file changed, 19 deletions(-)
> > 
> > diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
> > index 78175fe..9b9b6cf 100644
> > --- a/include/drm/tinydrm/tinydrm-helpers.h
> > +++ b/include/drm/tinydrm/tinydrm-helpers.h
> > @@ -44,28 +44,9 @@ void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
> >   				struct drm_framebuffer *fb,
> >   				struct drm_clip_rect *clip, bool swap);
> > -#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
> >   struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
> >   int tinydrm_enable_backlight(struct backlight_device *backlight);
> >   int tinydrm_disable_backlight(struct backlight_device *backlight);
> > -#else
> > -static inline struct backlight_device *
> > -tinydrm_of_find_backlight(struct device *dev)
> > -{
> > -	return NULL;
> > -}
> > -
> > -static inline int tinydrm_enable_backlight(struct backlight_device *backlight)
> > -{
> > -	return 0;
> > -}
> > -
> > -static inline int
> > -tinydrm_disable_backlight(struct backlight_device *backlight)
> > -{
> > -	return 0;
> > -}
> > -#endif
> >   size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len);
> >   bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw);
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch