Hi Am 15.05.23 um 10:59 schrieb Linus Walleij:
On Mon, May 15, 2023 at 10:17 AM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:Am 15.05.23 um 10:01 schrieb Linus Walleij:But the display is flickering like crazy so the updating frequency is totally off, which is because it does not scale down the resolution, the print used to be: Console: switching to colour frame buffer device 80x30 drm-clcd-pl111 c1000000.display: [drm] fb0: pl111drmfb frame buffer device It is now: Console: switching to colour frame buffer device 100x37 drm-clcd-pl111 c1000000.display: [drm] fb0: pl111drmfb frame buffer device 100x37! (i.e. 800x296), this display can only do 640x240. Any idea what else is going wrong here? Or is this another regression on top of the first regression ... I was under the impression that your change was only about formats not resolutions.If your display only supports 640x240, you should filter out all the other modes in the driver, if necessary. To me, that seems fix-worthy in any case.I think I found this, the bandwidth limit calculation in drivers/gpu/drm/pl111/pl111_display.c was using the bpp from the config and this was decreased from 16 to 15 and as it determined cpp by dividing bpp/8 this decreased from 2 bytes to 1 byte. Testing with DIV_ROUND_UP() in combination with the previous fix!
Great. It's the code in mode_valid, right? That fix should be good enough for now. In the long term, we could make some of the internal fb-helper code available to drivers. You'd then be able to use it to get the depth/bpp values for the color mode.
Best regards Thomas
Yours, Linus Walleij
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)
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