linux-kernel - Re: [PATCH v2 2/2] drm/ingenic: Fix driver not probing when IPU port is missing

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Message-Id: <AVKWFQ.TNMR0WH83TFS2@crapouillou.net>
Date:   Mon, 31 Aug 2020 02:47:34 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Ezequiel Garcia <ezequiel@...guardiasur.com.ar>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Sam Ravnborg <sam@...nborg.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        od@...c.me
Subject: Re: [PATCH v2 2/2] drm/ingenic: Fix driver not probing when IPU port
 is missing



Le dim. 30 août 2020 à 21:21, Ezequiel Garcia 
<ezequiel@...guardiasur.com.ar> a écrit :
> Hi Paul,
> 
> On Thu, 27 Aug 2020 at 09:04, Paul Cercueil <paul@...pouillou.net> 
> wrote:
>> 
>>  Even if support for the IPU was compiled in, we may run on a device
>>  (e.g. the Qi LB60) where the IPU is not available, or simply with 
>> an old
>>  devicetree without the IPU node. In that case the ingenic-drm 
>> refused to
>>  probe.
>> 
>>  Fix the driver so that it will probe even if the IPU node is not 
>> present
>>  in devicetree (but then IPU support is disabled of course).
>> 
>>  v2: Take a different approach
>> 
>>  Fixes: fc1acf317b01 ("drm/ingenic: Add support for the IPU")
>>  Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>  ---
>>   drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 19 +++++++++++--------
>>   1 file changed, 11 insertions(+), 8 deletions(-)
>> 
>>  diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c 
>> b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
>>  index c1bcb93aed2d..b7074161ccf0 100644
>>  --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
>>  +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
>>  @@ -673,7 +673,7 @@ static void ingenic_drm_unbind_all(void *d)
>>          component_unbind_all(priv->dev, &priv->drm);
>>   }
>> 
>>  -static int ingenic_drm_bind(struct device *dev)
>>  +static int ingenic_drm_bind(struct device *dev, bool 
>> has_components)
>>   {
>>          struct platform_device *pdev = to_platform_device(dev);
>>          const struct jz_soc_info *soc_info;
>>  @@ -808,7 +808,7 @@ static int ingenic_drm_bind(struct device *dev)
>>                          return ret;
>>                  }
>> 
>>  -               if (IS_ENABLED(CONFIG_DRM_INGENIC_IPU)) {
>>  +               if (IS_ENABLED(CONFIG_DRM_INGENIC_IPU) && 
>> has_components) {
>>                          ret = component_bind_all(dev, drm);
>>                          if (ret) {
>>                                  if (ret != -EPROBE_DEFER)
>>  @@ -939,6 +939,11 @@ static int ingenic_drm_bind(struct device *dev)
>>          return ret;
>>   }
>> 
>>  +static int ingenic_drm_bind_with_components(struct device *dev)
>>  +{
>>  +       return ingenic_drm_bind(dev, true);
>>  +}
>>  +
>>   static int compare_of(struct device *dev, void *data)
>>   {
>>          return dev->of_node == data;
>>  @@ -957,7 +962,7 @@ static void ingenic_drm_unbind(struct device 
>> *dev)
>>   }
>> 
>>   static const struct component_master_ops ingenic_master_ops = {
>>  -       .bind = ingenic_drm_bind,
>>  +       .bind = ingenic_drm_bind_with_components,
>>          .unbind = ingenic_drm_unbind,
>>   };
>> 
>>  @@ -968,14 +973,12 @@ static int ingenic_drm_probe(struct 
>> platform_device *pdev)
>>          struct device_node *np;
>> 
>>          if (!IS_ENABLED(CONFIG_DRM_INGENIC_IPU))
>>  -               return ingenic_drm_bind(dev);
>>  +               return ingenic_drm_bind(dev, false);
>> 
>>          /* IPU is at port address 8 */
>>          np = of_graph_get_remote_node(dev->of_node, 8, 0);
> 
> How about we get rid of this (seems a bit odd to rely on port 
> address) ?
> Rockchip-drm driver has a nice approach, and I think we might need
> something like that going forward, to support dw-hdmi.

The rockchip-drm approach works because all the sub-drivers must probe. 
In the case of ingenic-drm, even if the ingenic-drm driver was compiled 
with the ipu and dw-hdmi sub-drivers, you can't rely on these probing, 
as they are not present on e.g. the JZ4740.

Cheers,
-Paul