Message-ID: <CAOw6vbJVH4ePsJ5cOT0KcsZDBdM+MtqgTwmvYiM0EAExSLWWhQ@mail.gmail.com>
Date:	Thu, 3 Oct 2013 11:02:34 -0400
From:	Sean Paul <seanpaul@...omium.org>
To:	Inki Dae <inki.dae@...sung.com>
Cc:	DRI mailing list <dri-devel@...ts.freedesktop.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-doc@...r.kernel.org,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Dave Airlie <airlied@...ux.ie>
Subject: Re: [PATCH 4/5] drm/exynos: Initialize ptn3460 if present

On Thu, Oct 3, 2013 at 10:43 AM, Inki Dae <inki.dae@...sung.com> wrote:
> 2013/10/2 Sean Paul <seanpaul@...omium.org>:
>> This patch adds code to look for the ptn3460 in the device tree file on
>> exynos initialization. If ptn node is found, the driver will initialize
>> the ptn3460 driver and skip creating a DP connector (since the bridge
>> driver will register its own connector).
>>
>> Signed-off-by: Sean Paul <seanpaul@...omium.org>
>> ---
>>  drivers/gpu/drm/exynos/exynos_drm_core.c | 44 +++++++++++++++++++++++++++++++-
>>  1 file changed, 43 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/exynos/exynos_drm_core.c b/drivers/gpu/drm/exynos/exynos_drm_core.c
>> index 1bef6dc..9cf4476 100644
>> --- a/drivers/gpu/drm/exynos/exynos_drm_core.c
>> +++ b/drivers/gpu/drm/exynos/exynos_drm_core.c
>> @@ -12,7 +12,9 @@
>>   * option) any later version.
>>   */
>>
>> +#include <linux/of_i2c.h>
>>  #include <drm/drmP.h>
>> +#include <drm/bridge/ptn3460.h>
>>  #include "exynos_drm_drv.h"
>>  #include "exynos_drm_encoder.h"
>>  #include "exynos_drm_connector.h"
>> @@ -20,6 +22,40 @@
>>
>>  static LIST_HEAD(exynos_drm_subdrv_list);
>>
>> +struct bridge_init {
>> +       struct i2c_client *client;
>> +       struct device_node *node;
>> +};
>> +
>> +static bool find_bridge(const char *name, struct bridge_init *bridge)
>> +{
>> +       bridge->client = NULL;
>> +       bridge->node = of_find_node_by_name(NULL, name);
>
> Not clear to me. Why do you try to handle device tree here, not real
> device driver?. How about adding a output property to board specific
> fimd dt node: i.e. output = <&ptn3460_bridge>?

The problem doing something like this is that we won't have a handle
to drm_device if it's just a standalone driver, and so we won't be
able to register the bridge or connector. We need this init call one
way or another.


> Actually, the output
> device of fimd hw could be one of MIPI-DSI, eDP, mDNIe, LVDS bridge,
> or LCD. And then, let's find ptn3460-bridge node in the fimd driver,
> and initialize the ptn3460 bridge driver, and get power on or off
> through  exynos_drm_display_ops of the fimd driver. And all these
> codes could be hided from fimd driver by moving them into
> exynos_drm_display_ops. Of course, for this, you would need additional
> works. So let's do it if needed.
>
> The below is the outline of device tree I recommend,
>
> In board dts,
>        i2c@...D000 {
>              ptn3460_bridge: prn3460-bridge@20 {
>                     ...
>              }
>         }
>
>         fimd@...00000 {
>              ...
>              output_dev = <&ptn3460_bridge>;
>         }
>
> With this, I believe that you can do all things you want for
> controlling the LVDS bridge in fimd driver.
>

No, this isn't what I want to do. The bridge should not hang off fimd
since it's a crtc. The bridge should only be initialized by the DP
driver (it doesn't make sense to initialize ptn when you're using
MIPI/LVDS/whatever).

Since the actual crtc/encoder drivers are abstracted through
exynos_drm_core/crtc/encoder, we need to initialize the ptn driver in
the abstraction layers in order to hook it directly into drm.

Sean


> Thanks,
> Inki Dae
>
>> +       if (!bridge->node)
>> +               return false;
>> +
>> +       bridge->client = of_find_i2c_device_by_node(bridge->node);
>> +       if (!bridge->client)
>> +               return false;
>> +
>> +       return true;
>> +}
>> +
>> +/* returns the number of bridges attached */
>> +static int exynos_drm_attach_lcd_bridge(struct drm_device *dev,
>> +               struct drm_encoder *encoder)
>> +{
>> +       struct bridge_init bridge;
>> +       int ret;
>> +
>> +       if (find_bridge("ptn3460-bridge", &bridge)) {
>> +               ret = ptn3460_init(dev, encoder, bridge.client, bridge.node);
>> +               if (!ret)
>> +                       return 1;
>> +       }
>> +       return 0;
>> +}
>> +
>>  static int exynos_drm_create_enc_conn(struct drm_device *dev,
>>                                         struct exynos_drm_subdrv *subdrv)
>>  {
>> @@ -36,6 +72,13 @@ static int exynos_drm_create_enc_conn(struct drm_device *dev,
>>                 DRM_ERROR("failed to create encoder\n");
>>                 return -EFAULT;
>>         }
>> +       subdrv->encoder = encoder;
>> +
>> +       if (subdrv->manager->display_ops->type == EXYNOS_DISPLAY_TYPE_LCD) {
>> +               ret = exynos_drm_attach_lcd_bridge(dev, encoder);
>> +               if (ret)
>> +                       return 0;
>> +       }
>>
>>         /*
>>          * create and initialize a connector for this sub driver and
>> @@ -48,7 +91,6 @@ static int exynos_drm_create_enc_conn(struct drm_device *dev,
>>                 goto err_destroy_encoder;
>>         }
>>
>> -       subdrv->encoder = encoder;
>>         subdrv->connector = connector;
>>
>>         return 0;
>> --
>> 1.8.4
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@...ts.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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