[PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found

[Chen-Yu Tsai]

Hi Maxime,

On Tue, Aug 30, 2016 at 11:51 PM, Chen-Yu Tsai  wrote:
> On Tue, Aug 30, 2016 at 8:56 PM, Maxime Ripard
>  wrote:
>> Hi,
>>
>> On Tue, Aug 30, 2016 at 08:22:23PM +0800, Chen-Yu Tsai wrote:
>>> The KMS helpers (drm_atomic_helper_check_modeset/mode_fixup) pass
>>> encoder->bridge directly to drm_bridge_mode_fixup, which expects a
>>> valid pointer, or NULL (in which case it just returns).
>>>
>>> Clear encoder->bridge if a bridge is not found, instead of keeping
>>> the ERR_PTR value.
>>>
>>> Since other drm_bridge functions also follow this pattern of checking
>>> for a non-NULL pointer, we can drop the ifs around the calls and just
>>> pass the pointer directly.
>>>
>>> Fixes: 894f5a9f4b4a ("drm/sun4i: Add bridge support")
>>> Signed-off-by: Chen-Yu Tsai 
>>> ---
>>>  drivers/gpu/drm/sun4i/sun4i_rgb.c | 11 ++-
>>>  1 file changed, 6 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c 
>>> b/drivers/gpu/drm/sun4i/sun4i_rgb.c
>>> index d4e52522ec53..ee0795152a33 100644
>>> --- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
>>> +++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
>>> @@ -154,8 +154,7 @@ static void sun4i_rgb_encoder_enable(struct drm_encoder 
>>> *encoder)
>>>   if (!IS_ERR(tcon->panel))
>>>   drm_panel_enable(tcon->panel);
>>>
>>> - if (!IS_ERR(encoder->bridge))
>>> - drm_bridge_enable(encoder->bridge);
>>> + drm_bridge_enable(encoder->bridge);
>>>
>>>   sun4i_tcon_channel_enable(tcon, 0);
>>>  }
>>> @@ -170,8 +169,7 @@ static void sun4i_rgb_encoder_disable(struct 
>>> drm_encoder *encoder)
>>>
>>>   sun4i_tcon_channel_disable(tcon, 0);
>>>
>>> - if (!IS_ERR(encoder->bridge))
>>> - drm_bridge_disable(encoder->bridge);
>>> + drm_bridge_disable(encoder->bridge);
>>
>> I'd rather keep those changes, it makes it obvious that it's something
>> optionnal, that can be set to NULL.
>
> OK.

What about having a comment instead? Saves an extra branch condition,
while still showing that it's optional.

ChenYu

>
>>>   if (!IS_ERR(tcon->panel))
>>>   drm_panel_disable(tcon->panel);
>>> @@ -230,6 +228,9 @@ int sun4i_rgb_init(struct drm_device *drm)
>>>   return 0;
>>>   }
>>>
>>> + if (IS_ERR(encoder->bridge))
>>> + encoder->bridge = NULL;
>>> +
>>
>> And that could be the else condition of the if statement below.
>
> That would be a bit confusing, changing it after calling drm_encoder_init.
> The code says it ok to do though.
>
> ChenYu
>
>> Thanks!
>> Maxime
>>
>> --
>> Maxime Ripard, Free Electrons
>> Embedded Linux and Kernel engineering
>> http://free-electrons.com

[PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found

[Maxime Ripard]

On Wed, Aug 31, 2016 at 06:27:08PM +0200, Daniel Vetter wrote:
> > > >> + if (IS_ERR(encoder->bridge))
> > > >> + encoder->bridge = NULL;
> > > >> +
> > > >
> > > > And that could be the else condition of the if statement below.
> > > 
> > > That would be a bit confusing, changing it after calling drm_encoder_init.
> > > The code says it ok to do though.
> > 
> > The magic really happens only after the encoder has been attached to
> > something, so it's really safe.
> 
> s/attached/registered using drm_dev_register(). Which should
> happen _way_ later for all drivers which have gotten rid of their ->load
> callback and implemented the recommend driver load sequence.

My bad, thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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[PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found

[Maxime Ripard]

On Wed, Aug 31, 2016 at 07:09:23PM +0800, Chen-Yu Tsai wrote:
> >>>   sun4i_tcon_channel_disable(tcon, 0);
> >>>
> >>> - if (!IS_ERR(encoder->bridge))
> >>> - drm_bridge_disable(encoder->bridge);
> >>> + drm_bridge_disable(encoder->bridge);
> >>
> >> I'd rather keep those changes, it makes it obvious that it's something
> >> optionnal, that can be set to NULL.
> >
> > OK.
> 
> What about having a comment instead? Saves an extra branch condition,
> while still showing that it's optional.

I'm not sure we have to worry about an extra branch condition, but
yeah, that works for me.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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[PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found

[Daniel Vetter]

On Wed, Aug 31, 2016 at 05:40:02PM +0200, Maxime Ripard wrote:
> On Tue, Aug 30, 2016 at 11:51:26PM +0800, Chen-Yu Tsai wrote:
> > On Tue, Aug 30, 2016 at 8:56 PM, Maxime Ripard
> >  wrote:
> > > Hi,
> > >
> > > On Tue, Aug 30, 2016 at 08:22:23PM +0800, Chen-Yu Tsai wrote:
> > >> The KMS helpers (drm_atomic_helper_check_modeset/mode_fixup) pass
> > >> encoder->bridge directly to drm_bridge_mode_fixup, which expects a
> > >> valid pointer, or NULL (in which case it just returns).
> > >>
> > >> Clear encoder->bridge if a bridge is not found, instead of keeping
> > >> the ERR_PTR value.
> > >>
> > >> Since other drm_bridge functions also follow this pattern of checking
> > >> for a non-NULL pointer, we can drop the ifs around the calls and just
> > >> pass the pointer directly.
> > >>
> > >> Fixes: 894f5a9f4b4a ("drm/sun4i: Add bridge support")
> > >> Signed-off-by: Chen-Yu Tsai 
> > >> ---
> > >>  drivers/gpu/drm/sun4i/sun4i_rgb.c | 11 ++-
> > >>  1 file changed, 6 insertions(+), 5 deletions(-)
> > >>
> > >> diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c 
> > >> b/drivers/gpu/drm/sun4i/sun4i_rgb.c
> > >> index d4e52522ec53..ee0795152a33 100644
> > >> --- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
> > >> +++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
> > >> @@ -154,8 +154,7 @@ static void sun4i_rgb_encoder_enable(struct 
> > >> drm_encoder *encoder)
> > >>   if (!IS_ERR(tcon->panel))
> > >>   drm_panel_enable(tcon->panel);
> > >>
> > >> - if (!IS_ERR(encoder->bridge))
> > >> - drm_bridge_enable(encoder->bridge);
> > >> + drm_bridge_enable(encoder->bridge);
> > >>
> > >>   sun4i_tcon_channel_enable(tcon, 0);
> > >>  }
> > >> @@ -170,8 +169,7 @@ static void sun4i_rgb_encoder_disable(struct 
> > >> drm_encoder *encoder)
> > >>
> > >>   sun4i_tcon_channel_disable(tcon, 0);
> > >>
> > >> - if (!IS_ERR(encoder->bridge))
> > >> - drm_bridge_disable(encoder->bridge);
> > >> + drm_bridge_disable(encoder->bridge);
> > >
> > > I'd rather keep those changes, it makes it obvious that it's something
> > > optionnal, that can be set to NULL.
> > 
> > OK.
> > 
> > >>   if (!IS_ERR(tcon->panel))
> > >>   drm_panel_disable(tcon->panel);
> > >> @@ -230,6 +228,9 @@ int sun4i_rgb_init(struct drm_device *drm)
> > >>   return 0;
> > >>   }
> > >>
> > >> + if (IS_ERR(encoder->bridge))
> > >> + encoder->bridge = NULL;
> > >> +
> > >
> > > And that could be the else condition of the if statement below.
> > 
> > That would be a bit confusing, changing it after calling drm_encoder_init.
> > The code says it ok to do though.
> 
> The magic really happens only after the encoder has been attached to
> something, so it's really safe.

s/attached/registered using drm_dev_register(). Which should
happen _way_ later for all drivers which have gotten rid of their ->load
callback and implemented the recommend driver load sequence.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

[PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found

[Maxime Ripard]

On Tue, Aug 30, 2016 at 11:51:26PM +0800, Chen-Yu Tsai wrote:
> On Tue, Aug 30, 2016 at 8:56 PM, Maxime Ripard
>  wrote:
> > Hi,
> >
> > On Tue, Aug 30, 2016 at 08:22:23PM +0800, Chen-Yu Tsai wrote:
> >> The KMS helpers (drm_atomic_helper_check_modeset/mode_fixup) pass
> >> encoder->bridge directly to drm_bridge_mode_fixup, which expects a
> >> valid pointer, or NULL (in which case it just returns).
> >>
> >> Clear encoder->bridge if a bridge is not found, instead of keeping
> >> the ERR_PTR value.
> >>
> >> Since other drm_bridge functions also follow this pattern of checking
> >> for a non-NULL pointer, we can drop the ifs around the calls and just
> >> pass the pointer directly.
> >>
> >> Fixes: 894f5a9f4b4a ("drm/sun4i: Add bridge support")
> >> Signed-off-by: Chen-Yu Tsai 
> >> ---
> >>  drivers/gpu/drm/sun4i/sun4i_rgb.c | 11 ++-
> >>  1 file changed, 6 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c 
> >> b/drivers/gpu/drm/sun4i/sun4i_rgb.c
> >> index d4e52522ec53..ee0795152a33 100644
> >> --- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
> >> +++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
> >> @@ -154,8 +154,7 @@ static void sun4i_rgb_encoder_enable(struct 
> >> drm_encoder *encoder)
> >>   if (!IS_ERR(tcon->panel))
> >>   drm_panel_enable(tcon->panel);
> >>
> >> - if (!IS_ERR(encoder->bridge))
> >> - drm_bridge_enable(encoder->bridge);
> >> + drm_bridge_enable(encoder->bridge);
> >>
> >>   sun4i_tcon_channel_enable(tcon, 0);
> >>  }
> >> @@ -170,8 +169,7 @@ static void sun4i_rgb_encoder_disable(struct 
> >> drm_encoder *encoder)
> >>
> >>   sun4i_tcon_channel_disable(tcon, 0);
> >>
> >> - if (!IS_ERR(encoder->bridge))
> >> - drm_bridge_disable(encoder->bridge);
> >> + drm_bridge_disable(encoder->bridge);
> >
> > I'd rather keep those changes, it makes it obvious that it's something
> > optionnal, that can be set to NULL.
> 
> OK.
> 
> >>   if (!IS_ERR(tcon->panel))
> >>   drm_panel_disable(tcon->panel);
> >> @@ -230,6 +228,9 @@ int sun4i_rgb_init(struct drm_device *drm)
> >>   return 0;
> >>   }
> >>
> >> + if (IS_ERR(encoder->bridge))
> >> + encoder->bridge = NULL;
> >> +
> >
> > And that could be the else condition of the if statement below.
> 
> That would be a bit confusing, changing it after calling drm_encoder_init.
> The code says it ok to do though.

The magic really happens only after the encoder has been attached to
something, so it's really safe.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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[PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found

[Chen-Yu Tsai]

On Tue, Aug 30, 2016 at 8:56 PM, Maxime Ripard
 wrote:
> Hi,
>
> On Tue, Aug 30, 2016 at 08:22:23PM +0800, Chen-Yu Tsai wrote:
>> The KMS helpers (drm_atomic_helper_check_modeset/mode_fixup) pass
>> encoder->bridge directly to drm_bridge_mode_fixup, which expects a
>> valid pointer, or NULL (in which case it just returns).
>>
>> Clear encoder->bridge if a bridge is not found, instead of keeping
>> the ERR_PTR value.
>>
>> Since other drm_bridge functions also follow this pattern of checking
>> for a non-NULL pointer, we can drop the ifs around the calls and just
>> pass the pointer directly.
>>
>> Fixes: 894f5a9f4b4a ("drm/sun4i: Add bridge support")
>> Signed-off-by: Chen-Yu Tsai 
>> ---
>>  drivers/gpu/drm/sun4i/sun4i_rgb.c | 11 ++-
>>  1 file changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c 
>> b/drivers/gpu/drm/sun4i/sun4i_rgb.c
>> index d4e52522ec53..ee0795152a33 100644
>> --- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
>> +++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
>> @@ -154,8 +154,7 @@ static void sun4i_rgb_encoder_enable(struct drm_encoder 
>> *encoder)
>>   if (!IS_ERR(tcon->panel))
>>   drm_panel_enable(tcon->panel);
>>
>> - if (!IS_ERR(encoder->bridge))
>> - drm_bridge_enable(encoder->bridge);
>> + drm_bridge_enable(encoder->bridge);
>>
>>   sun4i_tcon_channel_enable(tcon, 0);
>>  }
>> @@ -170,8 +169,7 @@ static void sun4i_rgb_encoder_disable(struct drm_encoder 
>> *encoder)
>>
>>   sun4i_tcon_channel_disable(tcon, 0);
>>
>> - if (!IS_ERR(encoder->bridge))
>> - drm_bridge_disable(encoder->bridge);
>> + drm_bridge_disable(encoder->bridge);
>
> I'd rather keep those changes, it makes it obvious that it's something
> optionnal, that can be set to NULL.

OK.

>>   if (!IS_ERR(tcon->panel))
>>   drm_panel_disable(tcon->panel);
>> @@ -230,6 +228,9 @@ int sun4i_rgb_init(struct drm_device *drm)
>>   return 0;
>>   }
>>
>> + if (IS_ERR(encoder->bridge))
>> + encoder->bridge = NULL;
>> +
>
> And that could be the else condition of the if statement below.

That would be a bit confusing, changing it after calling drm_encoder_init.
The code says it ok to do though.

ChenYu

> Thanks!
> Maxime
>
> --
> Maxime Ripard, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com

[PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found

[Chen-Yu Tsai]

The KMS helpers (drm_atomic_helper_check_modeset/mode_fixup) pass
encoder->bridge directly to drm_bridge_mode_fixup, which expects a
valid pointer, or NULL (in which case it just returns).

Clear encoder->bridge if a bridge is not found, instead of keeping
the ERR_PTR value.

Since other drm_bridge functions also follow this pattern of checking
for a non-NULL pointer, we can drop the ifs around the calls and just
pass the pointer directly.

Fixes: 894f5a9f4b4a ("drm/sun4i: Add bridge support")
Signed-off-by: Chen-Yu Tsai 
---
 drivers/gpu/drm/sun4i/sun4i_rgb.c | 11 ++-
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c 
b/drivers/gpu/drm/sun4i/sun4i_rgb.c
index d4e52522ec53..ee0795152a33 100644
--- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
+++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
@@ -154,8 +154,7 @@ static void sun4i_rgb_encoder_enable(struct drm_encoder 
*encoder)
if (!IS_ERR(tcon->panel))
drm_panel_enable(tcon->panel);

-   if (!IS_ERR(encoder->bridge))
-   drm_bridge_enable(encoder->bridge);
+   drm_bridge_enable(encoder->bridge);

sun4i_tcon_channel_enable(tcon, 0);
 }
@@ -170,8 +169,7 @@ static void sun4i_rgb_encoder_disable(struct drm_encoder 
*encoder)

sun4i_tcon_channel_disable(tcon, 0);

-   if (!IS_ERR(encoder->bridge))
-   drm_bridge_disable(encoder->bridge);
+   drm_bridge_disable(encoder->bridge);

if (!IS_ERR(tcon->panel))
drm_panel_disable(tcon->panel);
@@ -230,6 +228,9 @@ int sun4i_rgb_init(struct drm_device *drm)
return 0;
}

+   if (IS_ERR(encoder->bridge))
+   encoder->bridge = NULL;
+
drm_encoder_helper_add(>encoder,
   _rgb_enc_helper_funcs);
ret = drm_encoder_init(drm,
@@ -266,7 +267,7 @@ int sun4i_rgb_init(struct drm_device *drm)
}
}

-   if (!IS_ERR(encoder->bridge)) {
+   if (encoder->bridge) {
encoder->bridge->encoder = >encoder;

ret = drm_bridge_attach(drm, encoder->bridge);
-- 
2.9.3

[PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found

[Maxime Ripard]

Hi,

On Tue, Aug 30, 2016 at 08:22:23PM +0800, Chen-Yu Tsai wrote:
> The KMS helpers (drm_atomic_helper_check_modeset/mode_fixup) pass
> encoder->bridge directly to drm_bridge_mode_fixup, which expects a
> valid pointer, or NULL (in which case it just returns).
> 
> Clear encoder->bridge if a bridge is not found, instead of keeping
> the ERR_PTR value.
> 
> Since other drm_bridge functions also follow this pattern of checking
> for a non-NULL pointer, we can drop the ifs around the calls and just
> pass the pointer directly.
> 
> Fixes: 894f5a9f4b4a ("drm/sun4i: Add bridge support")
> Signed-off-by: Chen-Yu Tsai 
> ---
>  drivers/gpu/drm/sun4i/sun4i_rgb.c | 11 ++-
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c 
> b/drivers/gpu/drm/sun4i/sun4i_rgb.c
> index d4e52522ec53..ee0795152a33 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
> @@ -154,8 +154,7 @@ static void sun4i_rgb_encoder_enable(struct drm_encoder 
> *encoder)
>   if (!IS_ERR(tcon->panel))
>   drm_panel_enable(tcon->panel);
>  
> - if (!IS_ERR(encoder->bridge))
> - drm_bridge_enable(encoder->bridge);
> + drm_bridge_enable(encoder->bridge);
>  
>   sun4i_tcon_channel_enable(tcon, 0);
>  }
> @@ -170,8 +169,7 @@ static void sun4i_rgb_encoder_disable(struct drm_encoder 
> *encoder)
>  
>   sun4i_tcon_channel_disable(tcon, 0);
>  
> - if (!IS_ERR(encoder->bridge))
> - drm_bridge_disable(encoder->bridge);
> + drm_bridge_disable(encoder->bridge);

I'd rather keep those changes, it makes it obvious that it's something
optionnal, that can be set to NULL.

>   if (!IS_ERR(tcon->panel))
>   drm_panel_disable(tcon->panel);
> @@ -230,6 +228,9 @@ int sun4i_rgb_init(struct drm_device *drm)
>   return 0;
>   }
>  
> + if (IS_ERR(encoder->bridge))
> + encoder->bridge = NULL;
> +

And that could be the else condition of the if statement below.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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