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Message-ID: <CADnq5_Mf4aMYcX07UfNVMDerna0rKeEVwT0mhNLerpUC58K2Yw@mail.gmail.com>
Date: Fri, 23 Mar 2012 15:42:44 -0400
From: Alex Deucher <alexdeucher@...il.com>
To: Lennert Buytenhek <buytenh@...tstofly.org>
Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: radeon + DVI->mDP converter + mDP display blank screen issue
since 3.0
On Fri, Mar 23, 2012 at 3:34 PM, Alex Deucher <alexdeucher@...il.com> wrote:
> On Fri, Mar 23, 2012 at 11:44 AM, Lennert Buytenhek
> <buytenh@...tstofly.org> wrote:
>> On Fri, Mar 23, 2012 at 10:59:27AM -0400, Alex Deucher wrote:
>>
>>> > Since Linux 3.0, a system with a Radeon HD 5450 (1002:68f9) connected
>>> > to a 27" Apple LED cinema display via an Atlona AT-DP400 Dual Link DVI
>>> > to Mini DisplayPort converter has started to stop giving screen
>>> > output on switching from text mode to graphical framebuffer during
>>> > system startup.
>>> >
>>> > I finally had some time to look at this, and it seems to have stopped
>>> > working after this commit:
>>> >
>>> > commit df271bec805b42527d864777ed035fcbb42e76c0
>>> > Author: Alex Deucher <alexdeucher@...il.com>
>>> > Date: Fri May 20 04:34:15 2011 -0400
>>> >
>>> > drm/radeon/kms: properly handle bpc >8 in atom command tables
>>> >
>>> > Signed-off-by: Alex Deucher <alexdeucher@...il.com>
>>> > Signed-off-by: Dave Airlie <airlied@...hat.com>
>>> >
>>> > ...and with the patch below (i.e. reverting part of the commit above)
>>> > applied to 3.3 I get screen output again.
>>> >
>>> > Even though the monitor seems to have an 8 bit panel, it reports 10
>>> > bits per channel in its EDID:
>>> >
>>> > [...]
>>> > Manufacturer: APP Model 9226 Serial Number 41959462
>>> > Made week 38 of 2010
>>> > EDID version: 1.4
>>> > Digital display
>>> > 10 bits per primary color channel
>>> > DisplayPort interface
>>> > Maximum image size: 60 cm x 34 cm
>>> > [...]
>>> >
>>> > The (active, dual link) DVI->mDP converter spec sheet says it supports
>>> > 24 bit color, and I'm guessing that it can't deal with 30. Is the
>>> > converter at fault here for passing through the EDID unchanged?
>>> >
>>> > Also, what would be the right way to handle this, a kernel command
>>> > line or module option to limit color depth or something like that?
>>> > ("Buy a video card with DP output." is a valid answer, I suppose.)
>>> >
>>> > I have no clue at all about graphics, and I have no idea whatsoever
>>> > what I'm doing here, but I just wanted to post this somewhere for
>>> > Google to find in case someone else runs into this!
>>>
>>> I've inquired with out display team on how to best handle this. In
>>> the meantime, it's probably best to just default to 8 bpc. Does the
>>> attached patch fix your issue?
>>
>> I've been using the patch below in a custom Fedora 17 kernel RPM, and
>> that seems to fix the issue. Your patch seems to be a superset of
>> this patch, so logically, your patch should do the trick as well. :)
>
> Can you try the attached patch on top of my previous one?
Scratch that. Try this one instead.
Alex
>
> Alex
>
>>
>>
>> thanks,
>> Lennert
>>
>>
>> diff -up linux-3.3.0-1.fc17.x86_64/drivers/gpu/drm/radeon/atombios_crtc.c.orig linux-3.3.0-1.fc17.x86_64/drivers/gpu/drm/radeon/atombios_crtc.c
>> --- linux-3.3.0-1.fc17.x86_64/drivers/gpu/drm/radeon/atombios_crtc.c.orig 2012-03-22 14:52:20.538854547 +0100
>> +++ linux-3.3.0-1.fc17.x86_64/drivers/gpu/drm/radeon/atombios_crtc.c 2012-03-22 14:55:39.740794113 +0100
>> @@ -550,8 +550,6 @@ static u32 atombios_adjust_pll(struct dr
>> if (encoder->crtc == crtc) {
>> radeon_encoder = to_radeon_encoder(encoder);
>> connector = radeon_get_connector_for_encoder(encoder);
>> - if (connector && connector->display_info.bpc)
>> - bpc = connector->display_info.bpc;
>> encoder_mode = atombios_get_encoder_mode(encoder);
>> is_duallink = radeon_dig_monitor_is_duallink(encoder, mode->clock);
>> if ((radeon_encoder->devices & (ATOM_DEVICE_LCD_SUPPORT | ATOM_DEVICE_DFP_SUPPORT)) ||
>> @@ -922,7 +920,6 @@ static void atombios_crtc_set_pll(struct
>> struct radeon_connector_atom_dig *dig_connector =
>> radeon_connector->con_priv;
>> int dp_clock;
>> - bpc = connector->display_info.bpc;
>>
>> switch (encoder_mode) {
>> case ATOM_ENCODER_MODE_DP_MST:
>>
>>
>>
>>> From 22ca454eb749968f266d6788a5f4778acc08cc66 Mon Sep 17 00:00:00 2001
>>> From: Alex Deucher <alexander.deucher@....com>
>>> Date: Fri, 23 Mar 2012 10:54:45 -0400
>>> Subject: [PATCH] drm/radeon/kms/atom: force bpc to 8 for now
>>>
>>> Using the bpc (bits per color) specified by the monitor
>>> can cause problems in some cases. Until we get a better
>>> handle on how to deal with those cases, just use a bpc of 8.
>>>
>>> Reported-by: Lennert Buytenhek <buytenh@...tstofly.org>
>>> Signed-off-by: Alex Deucher <alexander.deucher@....com>
>>> Cc: stable@...nel.org
>>> ---
>>> drivers/gpu/drm/radeon/atombios_crtc.c | 8 +++++---
>>> drivers/gpu/drm/radeon/atombios_dp.c | 3 +++
>>> drivers/gpu/drm/radeon/atombios_encoders.c | 4 ++--
>>> 3 files changed, 10 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
>>> index 083b3ea..b5ff1f7 100644
>>> --- a/drivers/gpu/drm/radeon/atombios_crtc.c
>>> +++ b/drivers/gpu/drm/radeon/atombios_crtc.c
>>> @@ -588,8 +588,8 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
>>> if (encoder->crtc == crtc) {
>>> radeon_encoder = to_radeon_encoder(encoder);
>>> connector = radeon_get_connector_for_encoder(encoder);
>>> - if (connector && connector->display_info.bpc)
>>> - bpc = connector->display_info.bpc;
>>> + /* if (connector && connector->display_info.bpc)
>>> + bpc = connector->display_info.bpc; */
>>> encoder_mode = atombios_get_encoder_mode(encoder);
>>> is_duallink = radeon_dig_monitor_is_duallink(encoder, mode->clock);
>>> if ((radeon_encoder->devices & (ATOM_DEVICE_LCD_SUPPORT | ATOM_DEVICE_DFP_SUPPORT)) ||
>>> @@ -965,7 +965,9 @@ static void atombios_crtc_set_pll(struct drm_crtc *crtc, struct drm_display_mode
>>> struct radeon_connector_atom_dig *dig_connector =
>>> radeon_connector->con_priv;
>>> int dp_clock;
>>> - bpc = connector->display_info.bpc;
>>> +
>>> + /* if (connector->display_info.bpc)
>>> + bpc = connector->display_info.bpc; */
>>>
>>> switch (encoder_mode) {
>>> case ATOM_ENCODER_MODE_DP_MST:
>>> diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
>>> index 6c62be2..c57d856 100644
>>> --- a/drivers/gpu/drm/radeon/atombios_dp.c
>>> +++ b/drivers/gpu/drm/radeon/atombios_dp.c
>>> @@ -405,10 +405,13 @@ static void dp_get_adjust_train(u8 link_status[DP_LINK_STATUS_SIZE],
>>> /* get bpc from the EDID */
>>> static int convert_bpc_to_bpp(int bpc)
>>> {
>>> +#if 0
>>> if (bpc == 0)
>>> return 24;
>>> else
>>> return bpc * 3;
>>> +#endif
>>> + return 24;
>>> }
>>>
>>> /* get the max pix clock supported by the link rate and lane num */
>>> diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
>>> index 468b874..e607c4d 100644
>>> --- a/drivers/gpu/drm/radeon/atombios_encoders.c
>>> +++ b/drivers/gpu/drm/radeon/atombios_encoders.c
>>> @@ -541,7 +541,7 @@ atombios_dig_encoder_setup(struct drm_encoder *encoder, int action, int panel_mo
>>> dp_clock = dig_connector->dp_clock;
>>> dp_lane_count = dig_connector->dp_lane_count;
>>> hpd_id = radeon_connector->hpd.hpd;
>>> - bpc = connector->display_info.bpc;
>>> + /* bpc = connector->display_info.bpc; */
>>> }
>>>
>>> /* no dig encoder assigned */
>>> @@ -1159,7 +1159,7 @@ atombios_external_encoder_setup(struct drm_encoder *encoder,
>>> dp_lane_count = dig_connector->dp_lane_count;
>>> connector_object_id =
>>> (radeon_connector->connector_object_id & OBJECT_ID_MASK) >> OBJECT_ID_SHIFT;
>>> - bpc = connector->display_info.bpc;
>>> + /* bpc = connector->display_info.bpc; */
>>> }
>>>
>>> memset(&args, 0, sizeof(args));
>>> --
>>> 1.7.7.5
>>>
View attachment "0001-drm-radeon-kms-improve-bpc-handling-v2.patch" of type "text/x-patch" (7360 bytes)
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