Re: [RFC 06/14] drm/i915: Disable vlank interrupt for disabling MIPI cmd mode

From: "Singh, Gaurav K" <gaurav.k.singh@intel.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Shobhit Kumar <shobhit.kumar@intel.com>,
	intel-gfx <intel-gfx@lists.freedesktop.org>
Subject: Re: [RFC 06/14] drm/i915: Disable vlank interrupt for disabling MIPI cmd mode
Date: Tue, 16 Jun 2015 22:24:57 +0530	[thread overview]
Message-ID: <558054E1.20602@intel.com> (raw)
In-Reply-To: <20150529172323.GW8341@phenom.ffwll.local>

On 5/29/2015 10:53 PM, Daniel Vetter wrote:
> On Fri, May 29, 2015 at 07:14:43PM +0200, Daniel Vetter wrote:
>> On Fri, May 29, 2015 at 04:06:58PM +0530, Gaurav K Singh wrote:
>>> vblank interrupt should be disabled before starting the disable
>>> sequence for MIPI command mode. Otherwise when pipe is disabled
>>> TE interurpt will be still handled and one memory write command
>>> will be sent with pipe disabled. This makes the pipe hw to get
>>> stuck and it doesn't recover in the next enable sequence causing
>>> display blank out.
>>>
>>> Signed-off-by: Yogesh Mohan Marimuthu <yogesh.mohan.marimuthu@intel.com>
>>> Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
>>> ---
>>>   drivers/gpu/drm/i915/intel_dsi.c |   14 ++++++++++++++
>>>   1 file changed, 14 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
>>> index 04d8ce0..aeea289 100644
>>> --- a/drivers/gpu/drm/i915/intel_dsi.c
>>> +++ b/drivers/gpu/drm/i915/intel_dsi.c
>>> @@ -513,11 +513,25 @@ static void intel_dsi_enable_nop(struct intel_encoder *encoder)
>>>   
>>>   static void intel_dsi_pre_disable(struct intel_encoder *encoder)
>>>   {
>>> +	struct drm_device *dev = encoder->base.dev;
>>>   	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
>>> +	struct intel_crtc *intel_crtc = to_intel_crtc(encoder->base.crtc);
>>> +	int pipe = intel_crtc->pipe;
>>>   	enum port port;
>>>   
>>>   	DRM_DEBUG_KMS("\n");
>>>   
>>> +	if (is_cmd_mode(intel_dsi)) {
>>> +		dev->driver->disable_vblank(dev, pipe);
>>> +
>>> +		/*
>>> +		 * Make sure that the last frame is sent otherwise pipe can get
>>> +		 * stuck. Currently providing delay time for ~2 vblanks
>>> +		 * assuming 60fps.
>>> +		 */
>>> +		mdelay(40);
>>> +	}
>> Nope. You need to move around the drm_vblank_off suitably, only that
>> function correctly handles all the book-keeping around vblank interrupts.
>> If this doesn't work out because of ordering we need to dig into this and
>> figure out something. Worst case we need to push the drm_vblank_off call
>> into encoder callbacks for everyone. That's something we already discussed
>> but then decided against.
> I seem to be blind, but where exactly is that vblank-driven upload code?
> -Daniel
Hi Daniel,

dev->driver->disable_vblank calls valleyview_disable_vblank which already exists. But I did check with drm_vblank_off, it seems to work fine.

I will float the updated patch shortly.

With regards,
Gaurav

>> -Daniel
>>
>>> +
>>>   	if (is_vid_mode(intel_dsi)) {
>>>   		/* Send Shutdown command to the panel in LP mode */
>>>   		for_each_dsi_port(port, intel_dsi->ports)
>>> -- 
>>> 1.7.9.5
>>>
>>> _______________________________________________
>>> Intel-gfx mailing list
>>> Intel-gfx@lists.freedesktop.org
>>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>> -- 
>> Daniel Vetter
>> Software Engineer, Intel Corporation
>> http://blog.ffwll.ch

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx