[linux-sunxi] [PATCH 3/6] drm/sun4i: dsi: Add bridge support

[Sergey Suloev]

Hi, Jagan,

On 3/15/19 4:45 PM, Maxime Ripard wrote:
> On Fri, Mar 15, 2019 at 02:32:55PM +0100, Paul Kocialkowski wrote:
>> Hi,
>>
>> On Fri, 2019-03-15 at 18:38 +0530, Jagan Teki wrote:
>>> Some display panels would come up with a non-DSI output which
>>> can have an option to connect DSI interface by means of bridge
>>> convertor.
>>>
>>> This DSI to non-DSI bridge convertor would require a bridge
>>> driver that would communicate the DSI controller for bridge
>>> functionalities.
>>>
>>> So, add support for bridge functionalities in Allwinner DSI
>>> controller.
>> See a few comments below.
>>
>>> Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
>>> ---
>>>   drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 65 +++++++++++++++++++-------
>>>   drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h |  1 +
>>>   2 files changed, 49 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
>>> index 0960b96b62cc..64d74313b842 100644
>>> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
>>> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
>>> @@ -781,6 +781,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
>>>   	if (!IS_ERR(dsi->panel))
>>>   		drm_panel_prepare(dsi->panel);
>>>   
>>> +	if (!IS_ERR(dsi->bridge))
>>> +		drm_bridge_pre_enable(dsi->bridge);
>>> +
>>>   	/*
>>>   	 * FIXME: This should be moved after the switch to HS mode.
>>>   	 *
>>> @@ -796,6 +799,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
>>>   	if (!IS_ERR(dsi->panel))
>>>   		drm_panel_enable(dsi->panel);
>>>   
>>> +	if (!IS_ERR(dsi->bridge))
>>> +		drm_bridge_enable(dsi->bridge);
>>> +
>>>   	sun6i_dsi_start(dsi, DSI_START_HSC);
>>>   
>>>   	udelay(1000);
>>> @@ -812,6 +818,9 @@ static void sun6i_dsi_encoder_disable(struct drm_encoder *encoder)
>>>   	if (!IS_ERR(dsi->panel)) {
>>>   		drm_panel_disable(dsi->panel);
>>>   		drm_panel_unprepare(dsi->panel);
>>> +	} else if (!IS_ERR(dsi->bridge)) {
>>> +		drm_bridge_disable(dsi->bridge);
>>> +		drm_bridge_post_disable(dsi->bridge);
>>>   	}
>>>   
>>>   	phy_power_off(dsi->dphy);
>>> @@ -973,11 +982,16 @@ static int sun6i_dsi_attach(struct mipi_dsi_host *host,
>>>   	struct sun6i_dsi *dsi = host_to_sun6i_dsi(host);
>>>   
>>>   	dsi->device = device;
>>> -	dsi->panel = of_drm_find_panel(device->dev.of_node);
>>> -	if (IS_ERR(dsi->panel))
>>> -		return PTR_ERR(dsi->panel);
>>>   
>>> -	dev_info(host->dev, "Attached device %s\n", device->name);
>>> +	dsi->bridge = of_drm_find_bridge(device->dev.of_node);
>>> +	if (!dsi->bridge) {
>> You are using IS_ERR to check that the bridge is alive in the changes
>> above, but switch to checking that it's non-NULL at this point.
>>
>> Are both guaranteed to be interchangeable?
> They aren't. Any ERR_PTR will be !NULL
>
>>> +		dsi->panel = of_drm_find_panel(device->dev.of_node);
>>> +		if (IS_ERR(dsi->panel))
>>> +			return PTR_ERR(dsi->panel);
>>> +	}
>> You should probably use drm_of_find_panel_or_bridge instead of
>> duplicating the logic here.
> Or we can even use the drm_panel_bridge_add to simplify things.

this approach is implemented by E.Anholt in VC4 dsi driver and it looks 
nice.

>
> Maxime
>
>
> _______________________________________________
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> linux-arm-kernel at lists.infradead.org
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