Thread (40 messages) 40 messages, 6 authors, 2019-10-01

Re: [PATCH] drm/omap: Migrate minimum FCK/PCK ratio from Kconfig to dts

From: Tomi Valkeinen <hidden>
Date: 2019-09-27 15:48:05
Also in: dri-devel, linux-omap, lkml

On 27/09/2019 18:37, Tero Kristo wrote:
If you can provide details about what clock framework / driver does 
wrong (sample clk_set_xyz call sequence, expected results via 
clk_get_xyz, and what fails), I can take a look at it. Just reporting 
arbitrary display driver issues I won't be able to debug at all (I don't 
have access to any of the displays, nor do I want to waste time 
debugging them without absolutely no knowledge whatsoever.)
I used your hack patches to allow changing rates via debugfs. And set 
dss1_alwon_fck_3430es2 to 27000000 or 27870967. The end result was that 
DSS gets some very high clock from dss1_alwon_fck_3430es2, as the frame 
rate jumps to many hundreds fps.

So, these numbers are not real, but to give the idea what I saw. Running 
first with 50 MHz, I can see, say, 40 fps. Then I set the clock to 30 
MHz, and fps dropped to, say, 30fps, as expected with lower clock. Then 
I set the clock to 27MHz (or the other one), expecting a bit lower fps, 
but instead I saw hundreds of fps.

I don't know if there's any other way to observe the wrong clock rate 
but have the dss enabled and running kmstest or similar. I can help you 
set that up next week, should be trivial. You don't need a display for that.

  Tomi

-- 
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
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