Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc

From	Peter Ujfalusi <peter.ujfalusi@ti.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc
Date	2016-10-05 10:10 +0200
Message-ID	<soPr4-6yF-3@gated-at.bofh.it> (permalink)
References	(1 earlier) <smMxk-6vr-3@gated-at.bofh.it> <sn5JE-2d7-31@gated-at.bofh.it> <sn7BL-3nt-13@gated-at.bofh.it> <snbFn-67s-15@gated-at.bofh.it> <soucW-Mv-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 10/04/16 12:20, Bartosz Golaszewski wrote:
> 2016-09-30 21:19 GMT+02:00 Peter Ujfalusi <peter.ujfalusi@ti.com>:
>> On 09/30/2016 06:06 PM, Bartosz Golaszewski wrote:
>>>
>>> Just ran a quick test with speaker-test -c2 -twav. Besides the fact
>>> that the left and right channels are inverted (I'm looking into that),
>>> I didn't notice any problems. Even at 1024x768 resolution, playing
>>> audio at the same time seems to work fine.
>>
> 
> Hi Peter
> 
>> That's good to hear, but I think the priorities should be set:
>> LCDC and EDMA30TC1 to highest priority
>> EDMA30TC0 to priority 2
>>
>> The 0TC0 is used by MMC and if you want to play a video you might need the
>> servicing TC to be higher priority then other masters.
>>
>> If audio playback would trigger sync losts in lcdc then we might need to move
>> 0TC1 to priority 1.
>>
> 
> Did you mean "set EDMA31TC0 to priority 2"? EDMA30TC0 is already at
> the highest priority. Or did you mean that we need to lower the
> EDMA30TC0 priority? In that case: is 2 the correct value? EDMA31TC0 is
> used by mmc1 and its priority is 4. Shouldn't we set both to be the
> same?

What I mean is:
EMDA30TC1 = LCDC = 0;
EDMA30TC0 = 2;

I don't know what the MMC1 is used on the LCDK, but it is only used by add-on
card on Logic's OMAP-L138 EVM (wifi if I recall right). I would leave
EDMA31TC0 as 4.

And while we are here: this is my problem, I don't want LCDC to be high
priority on OMAP-L138 EVM as it has no display by default, no point of
fiddling with the EMIF priority there.

This is the reason why we should have a way via DT to set these priorities. A
DT fragment for OMAP-L138 EVM's wifi module might want to increase the
EDMA31TC0 priority to get better throughput, but on a bare board we don't want
that. If I would have the display module for the EVM, I would like to rise the
LCDC priority also, but I don't have one. If I have the aduio add-on module I
would want to keep audio as the highest priority (and the MMC0 to be able to
record/play audio files). etc.

>> I agree that LCDC priority needs to be higher, but I do wonder why the default
>> (5) is not working and if it is not working why it is 5...
>>
>> My guess is that the change in the PBBPR register is the one actually helping
>> here.
>>
> 
> While it seems that lowering the EDMA30TC0 priority is indeed
> unnecessary, if I don't set the LCDC master to priority 0, I still get
> FIFO underflows even with the change in PBBPR.

I believe it is valid to raise the LCDC priority, but I wonder what blocks the
LCDC accesses when you don't really have anything going on in the background.

-- 
Péter

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-29 18:40 +0200
  Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Karl Beldan <karl.beldan@gmail.com> - 2016-09-29 21:10 +0200
    Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-30 11:40 +0200
      Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Karl Beldan <karl.beldan@gmail.com> - 2016-09-30 11:40 +0200
  Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Peter Ujfalusi <peter.ujfalusi@ti.com> - 2016-09-30 15:10 +0200
    Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-30 17:10 +0200
      Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Peter Ujfalusi <peter.ujfalusi@ti.com> - 2016-09-30 21:30 +0200
        Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Sekhar Nori <nsekhar@ti.com> - 2016-10-01 11:30 +0200
          Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Peter Ujfalusi <peter.ujfalusi@ti.com> - 2016-10-03 09:20 +0200
            Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Kevin Hilman <khilman@baylibre.com> - 2016-10-04 15:10 +0200
              Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Peter Ujfalusi <peter.ujfalusi@ti.com> - 2016-10-05 10:30 +0200
                Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Sekhar Nori <nsekhar@ti.com> - 2016-10-06 20:00 +0200
        Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-10-04 11:30 +0200
          Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc Peter Ujfalusi <peter.ujfalusi@ti.com> - 2016-10-05 10:10 +0200

csiph-web