Hi Am 26.09.22 um 12:34 schrieb Geert Uytterhoeven:
Hi Maxime,On Mon, Sep 26, 2022 at 12:17 PM Maxime Ripard <max...@cerno.tech> wrote:On Fri, Sep 23, 2022 at 11:05:48AM +0200, Thomas Zimmermann wrote:+ /* 63.556us * 13.5MHz = 858 pixels */I kind of get what the comment wants to tell me, but the units don't add up.I'm not sure how it doesn't add up? We have a frequency in Hz (equivalent to s^-1) and a duration in s, so the result ends up with no dimension, which is to be expected for a number of periods?To make the units add up, it should be 13.5 Mpixel/s (which is what a pixel clock of 13.5 MHz really means ;-)
Sort of. It leaves the time value as a magic number, which obfuscates what's happening.
The unit for htotal is pixels/scanline because if you multiply it with the number of scanlines per frame (which is in vtotal), you get pixels/frame. Multiplying with the frames per second results in the pixel clock in pixels/second.
That's a bit much for this comment. Hence, I suggested to remove these comments entirely and document the relation among the numbers in a more prominent location. The documentation for drm_display_mode would be a good place, I guess.
Best regards Thomas
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
OpenPGP_signature
Description: OpenPGP digital signature
