From: Archit Taneja <architt@codeaurora.org>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org,
Jose Abreu <Jose.Abreu@synopsys.com>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Alexey Brodkin <Alexey.Brodkin@synopsys.com>,
linux-kernel@vger.kernel.org,
Carlos Palminha <CARLOS.PALMINHA@synopsys.com>
Subject: Re: [PATCH v2 6/8] drm: Introduce drm_bridge_mode_valid()
Date: Mon, 15 May 2017 09:48:52 +0530 [thread overview]
Message-ID: <6490c0e0-d69c-fbd0-7bbe-583fec6386f9@codeaurora.org> (raw)
In-Reply-To: <2203839.UYlrXxpDjl@avalon>
On 05/12/2017 04:31 PM, Laurent Pinchart wrote:
> Hi Archit,
>
> On Friday 12 May 2017 16:20:07 Archit Taneja wrote:
>> On 05/12/2017 03:08 PM, Laurent Pinchart wrote:
>>> On Wednesday 10 May 2017 17:14:33 Daniel Vetter wrote:
>>>> On Wed, May 10, 2017 at 04:41:09PM +0300, Ville Syrjälä wrote:
>>>>> On Tue, May 09, 2017 at 06:00:13PM +0100, Jose Abreu wrote:
>>>>>> Introduce a new helper function which calls mode_valid() callback
>>>>>> for all bridges in an encoder chain.
>>>>>>
>>>>>> Signed-off-by: Jose Abreu <joabreu@synopsys.com>
>>>>>> Cc: Carlos Palminha <palminha@synopsys.com>
>>>>>> Cc: Alexey Brodkin <abrodkin@synopsys.com>
>>>>>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>>>>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>>>> Cc: Dave Airlie <airlied@linux.ie>
>>>>>> Cc: Andrzej Hajda <a.hajda@samsung.com>
>>>>>> Cc: Archit Taneja <architt@codeaurora.org>
>>>>>> ---
>>>>>>
>>>>>> drivers/gpu/drm/drm_bridge.c | 33 +++++++++++++++++++++++++++++++++
>>>>>> include/drm/drm_bridge.h | 2 ++
>>>>>> 2 files changed, 35 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/drm_bridge.c
>>>>>> b/drivers/gpu/drm/drm_bridge.c
>>>>>> index 86a7637..dc8cdfe 100644
>>>>>> --- a/drivers/gpu/drm/drm_bridge.c
>>>>>> +++ b/drivers/gpu/drm/drm_bridge.c
>>>>>> @@ -206,6 +206,39 @@ bool drm_bridge_mode_fixup(struct drm_bridge
>>>>>> *bridge,
>>>>>>
>>>>>> EXPORT_SYMBOL(drm_bridge_mode_fixup);
>>>>>>
>>>>>> /**
>>>>>>
>>>>>> + * drm_bridge_mode_valid - validate the mode against all bridges in
>>>>>> the
>>>>>> + * encoder chain.
>>>>>> + * @bridge: bridge control structure
>>>>>> + * @mode: desired mode to be validated
>>>>>> + *
>>>>>> + * Calls &drm_bridge_funcs.mode_valid for all the bridges in the
>>>>>> encoder
>>>>>> + * chain, starting from the first bridge to the last. If at least one
>>>>>> bridge + * does not accept the mode the function returns the error
>>>>>> code.
>>>>>> + *
>>>>>> + * Note: the bridge passed should be the one closest to the encoder.
>>>>>> + *
>>>>>> + * RETURNS:
>>>>>> + * MODE_OK on success, drm_mode_status Enum error code on failure
>>>>>> + */
>>>>>> +enum drm_mode_status drm_bridge_mode_valid(struct drm_bridge *bridge,
>>>>>> + const struct
> drm_display_mode
>>>
>>> *mode)
>>>
>>>>>> +{
>>>>>> + enum drm_mode_status ret = MODE_OK;
>>>>>> +
>>>>>> + if (!bridge)
>>>>>> + return ret;
>>>>>> +
>>>>>> + if (bridge->funcs->mode_valid)
>>>>>> + ret = bridge->funcs->mode_valid(bridge, mode);
>>>>>> +
>>>>>> + if (ret != MODE_OK)
>>>>>> + return ret;
>>>>>> +
>>>>>> + return drm_bridge_mode_valid(bridge->next, mode);
>>>>>
>>>>> Looks like it should be pretty trivial to avoid the recursion.
>>>>>
>>>>> Am I correct in interpreting this that bridges have some kind of
>>>>> a hand rolled linked list implementation? Reusing the standard
>>>>> linked lists would allow you to use list_for_each() etc.
>>>>
>>>> Yeah it's a hand-rolled list, but current hw also has a bridge nesting
>>>> depth of 2, so it really doesn't matter. I guess once we have real long
>>>> chains of bridges we can fix this (and just using list_head sounds like a
>>>> great idea).
>>>
>>> Even if not really needed right now, it's a pretty easy cleanup, if Jose
>>> has time to handle it in v3 of this series let's not postpone it ;-)
>>
>> jfyi, some of the bridge functions call the ops from the last bridge in the
>> chain to first, so we'd need to use list_for_each_entry_prev() (or something
>> like that) for them.
>
> And now that I think about it, for some of the operations (especially
> enable/disable) I believe that the bridge should be able to decide whether to
> call the next/previous bridge first or to configure its hardware first. I can
> image bridges that need the previous bridge in the chain to provide a valid
> clock before they get started, as well as bridges that need to be started with
> the incoming video signal stopped.
I guess converting into list would be a good start to achieve this. We'd probably
need to extend/redo the drm_bridge_attach() API to tweak the order in the which
the ops are called.
Thanks,
Archit
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2017-05-15 4:19 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-09 17:00 [PATCH v2 0/8] Introduce new mode validation callbacks Jose Abreu
2017-05-09 17:00 ` [PATCH v2 1/8] drm: Add crtc/encoder/bridge->mode_valid() callbacks Jose Abreu
2017-05-10 8:03 ` Daniel Vetter
2017-05-10 9:05 ` Jose Abreu
2017-05-12 8:24 ` Laurent Pinchart
2017-05-15 6:46 ` Daniel Vetter
2017-05-09 17:00 ` [PATCH v2 2/8] drm: Add drm_crtc_mode_valid() Jose Abreu
2017-05-10 7:59 ` Daniel Vetter
2017-05-10 8:57 ` Jose Abreu
2017-05-10 15:12 ` Daniel Vetter
2017-05-09 17:00 ` [PATCH v2 3/8] drm: Add drm_encoder_mode_valid() Jose Abreu
2017-05-09 17:00 ` [PATCH v2 4/8] drm: Add drm_connector_mode_valid() Jose Abreu
2017-05-09 17:00 ` [PATCH v2 5/8] drm: Use new mode_valid() helpers in connector probe helper Jose Abreu
2017-05-10 8:01 ` Daniel Vetter
2017-05-10 8:59 ` Jose Abreu
2017-05-12 9:35 ` Laurent Pinchart
2017-05-12 16:06 ` Jose Abreu
2017-05-14 11:04 ` Laurent Pinchart
2017-05-15 6:47 ` Daniel Vetter
2017-05-15 7:05 ` Laurent Pinchart
2017-05-16 5:11 ` Jose Abreu
2017-05-09 17:00 ` [PATCH v2 6/8] drm: Introduce drm_bridge_mode_valid() Jose Abreu
2017-05-10 13:41 ` Ville Syrjälä
2017-05-10 14:01 ` Jose Abreu
2017-05-10 14:07 ` Jose Abreu
2017-05-10 15:14 ` Daniel Vetter
2017-05-12 9:38 ` Laurent Pinchart
2017-05-12 10:50 ` Archit Taneja
2017-05-12 11:01 ` Laurent Pinchart
2017-05-15 4:18 ` Archit Taneja [this message]
2017-05-15 6:49 ` Daniel Vetter
2017-05-09 17:00 ` [PATCH v2 7/8] drm: Use mode_valid() in atomic modeset Jose Abreu
2017-05-10 16:08 ` Archit Taneja
2017-05-10 17:55 ` Daniel Vetter
2017-05-12 9:53 ` Laurent Pinchart
2017-05-15 6:50 ` Daniel Vetter
2017-05-09 17:00 ` [PATCH v2 8/8] drm: arc: Use crtc->mode_valid() callback Jose Abreu
2017-05-12 9:57 ` Laurent Pinchart
2017-05-15 1:40 ` Jose Abreu
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