From: Clint Taylor <clinton.a.taylor@intel.com>
To: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: Intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH v2] drm/i915: Audio N value computed for pixel doubled modes
Date: Mon, 06 Oct 2014 15:01:46 -0700 [thread overview]
Message-ID: <5433114A.1010001@intel.com> (raw)
In-Reply-To: <20140926162853.GB32511@intel.com>
On 09/26/2014 09:28 AM, Ville Syrjälä wrote:
> On Thu, Sep 25, 2014 at 09:26:36AM -0700, clinton.a.taylor@intel.com wrote:
>> From: Clint Taylor <clinton.a.taylor@intel.com>
>>
>> HDMI audio clock config was incorrectly choosing the default for
>> pixel doubled interlaced modes. The table was missing pixel clock
>> values 13.500 (27.000) and 13.513 (27.027). Luckily the default N
>> value for 25.200 is the same N value for both 27MHz pixel clocks,
>> a warning message was being printed with drm.debug set.
>>
>> ver2: Use 13500 * 1001 / 1000 instead of 13513 constant.
>>
>> Cc: Jani Nikula <jani.nikula at intel.com>
>>
>> Signed-off-by: Clint Taylor <clinton.a.taylor@intel.com>
>> ---
>> drivers/gpu/drm/i915/intel_display.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index 858011d..e76a4106 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -7872,6 +7872,8 @@ static struct {
>> { 74250, AUD_CONFIG_PIXEL_CLOCK_HDMI_74250 },
>> { DIV_ROUND_UP(148500 * 1000, 1001), AUD_CONFIG_PIXEL_CLOCK_HDMI_148352 },
>> { 148500, AUD_CONFIG_PIXEL_CLOCK_HDMI_148500 },
>> + { 13500, AUD_CONFIG_PIXEL_CLOCK_HDMI_27000 },
>> + { 13500 * 1001 / 1000, AUD_CONFIG_PIXEL_CLOCK_HDMI_27027 },
>
> We have double clocked modes where the non-doubled clock is already
> 27MHz so this seems like a bandaid for one particular case rather than a
> full solution.
>
> The HDMI specification makes it clear that the N/CTS stuff depends on
> the TMDS clock and not the pixel clock, but BSpec just talks about pixel
> clock without further explaining any of this stuff. So should we look
> at port_clock rather than the pixel clock here?
No, Since we support 12bpc we still need to only worry about the pixel
clock. TMDS clock and port clock will be multiplied by 1.5 in 12bpc
mode, but the N value remains the same as the 8bpc clock.
-Clint
>
>> };
>>
>> /* get AUD_CONFIG_PIXEL_CLOCK_HDMI_* value for mode */
>> --
>> 1.7.9.5
>>
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
next prev parent reply other threads:[~2014-10-06 22:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-24 22:35 [PATCH] drm/i915: Audio N value computed for pixel doubled modes clinton.a.taylor
2014-09-25 6:46 ` Jani Nikula
2014-09-25 16:26 ` [PATCH v2] " clinton.a.taylor
2014-09-26 16:28 ` Ville Syrjälä
2014-10-06 22:01 ` Clint Taylor [this message]
2014-10-07 8:52 ` Ville Syrjälä
2014-10-13 23:46 ` Clint Taylor
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