linux-kernel - Re: [Intel-gfx] [PATCH] drm/i915: Clear pipe's pll hw state in hsw_dp_set_ddi_pll_sel()

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Message-ID: <87pp4d2ogi.fsf@intel.com>
Date:	Tue, 30 Jun 2015 18:41:33 +0300
From:	Jani Nikula <jani.nikula@...ux.intel.com>
To:	Daniel Vetter <daniel@...ll.ch>
Cc:	Ander Conselvan de Oliveira 
	<ander.conselvan.de.oliveira@...el.com>,
	Dave Airlie <airlied@...ux.ie>,
	intel-gfx <intel-gfx@...ts.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	DRI mailing list <dri-devel@...ts.freedesktop.org>,
	Daniel Vetter <daniel.vetter@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [Intel-gfx] [PATCH] drm/i915: Clear pipe's pll hw state in hsw_dp_set_ddi_pll_sel()

On Tue, 30 Jun 2015, Daniel Vetter <daniel@...ll.ch> wrote:
> On Tue, Jun 30, 2015 at 04:47:06PM +0300, Jani Nikula wrote:
>> On Tue, 30 Jun 2015, Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@...el.com> wrote:
>> > Similarly to what is done for SKL, clear the dpll_hw_state of the pipe
>> > config in hsw_dp_set_ddi_pll_sel(), since it main contain stale values.
>> > That can happen if a crtc that was previously driving an HDMI connector
>> > switches to a DP connector. In that case, the wrpll field was left with
>> > its old value, leading to warnings like the one below:
>> >
>> > [drm:check_crtc_state [i915]] *ERROR* mismatch in dpll_hw_state.wrpll (expected 0xb035061f, found 0x00000000)
>> > ------------[ cut here ]------------
>> > WARNING: CPU: 1 PID: 767 at drivers/gpu/drm/i915/intel_display.c:12324 check_crtc_state+0x975/0x10b0 [i915]()
>> > pipe state doesn't match!
>> >
>> > This regression was indroduced in
>> >
>> > commit dd3cd74acf12723045a64f1f2c6298ac7b34a5d5
>> > Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@...el.com>
>> > Date:   Fri May 15 13:34:29 2015 +0300
>> >
>> >     drm/i915: Don't overwrite (e)DP PLL selection on SKL
>> >
>> > Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@...el.com>
>> 
>> Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
>> Tested-by: Jani Nikula <jani.nikula@...el.com>
>
> Yeah makes sense as a fix for 4.2. But for 4.3 I wonder whether the
> original commit that started this chain needs to be changed a bit:
>
> commit 4978cc93d9ac240b435ce60431aef24239b4c270
> Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@...el.com>
> Date:   Tue Apr 21 17:13:21 2015 +0300
>
>     drm/i915: Preserve shared DPLL information in new pipe_config
>
> All the trouble this caused is because it not only preserves the sharing
> config (in crtc_state->shared_dpll) but also the ->dpll_hw_state. And I
> think with Maarten's latest code (for 4.3) we'd just do an unconditional
> compute_config (need it for fast pfit updates and fastboot), which means
> the bogus values in ->dpll_hw_state aren't a problem any more since we'll
> overwrite them again. And then we could remove that sprinkle of memsets we
> have all over, which would be good (since the current approach is
> obviously a bit fragile). Anyway:
>
> Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>

Pushed to drm-intel-next-fixes, thanks for the patch and review. One
down, another one left to fix.

BR,
Jani.

>
> Thanks, Daniel
>
>> 
>> > ---
>> >
>> > Only compile tested, for the wrpll warning.
>> >
>> > Thanks,
>> > Ander
>> >
>> >  drivers/gpu/drm/i915/intel_dp.c | 3 +++
>> >  1 file changed, 3 insertions(+)
>> >
>> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> > index 4ebfc3a..fbd9ac3 100644
>> > --- a/drivers/gpu/drm/i915/intel_dp.c
>> > +++ b/drivers/gpu/drm/i915/intel_dp.c
>> > @@ -1147,6 +1147,9 @@ skl_edp_set_pll_config(struct intel_crtc_state *pipe_config, int link_clock)
>> >  static void
>> >  hsw_dp_set_ddi_pll_sel(struct intel_crtc_state *pipe_config, int link_bw)
>> >  {
>> > +	memset(&pipe_config->dpll_hw_state, 0,
>> > +	       sizeof(pipe_config->dpll_hw_state));
>> > +
>> >  	switch (link_bw) {
>> >  	case DP_LINK_BW_1_62:
>> >  		pipe_config->ddi_pll_sel = PORT_CLK_SEL_LCPLL_810;
>> > -- 
>> > 2.1.0
>> >
>> 
>> -- 
>> Jani Nikula, Intel Open Source Technology Center
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@...ts.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Jani Nikula, Intel Open Source Technology Center
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