On Fri, Jun 14, 2019 at 7:54 PM Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > On Wed, Jun 05, 2019 at 01:03:16PM +0530, Jagan Teki wrote: > > On Wed, Jun 5, 2019 at 12:19 PM Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > > > > > Hi, > > > > > > I've reordered the mail a bit to work on chunks > > > > > > On Fri, May 24, 2019 at 03:37:42PM +0530, Jagan Teki wrote: > > > > > I wish it was in your commit log in the first place, instead of having > > > > > to exchange multiple mails over this. > > > > > > > > > > However, I don't think that's quite true, and it might be a bug in > > > > > Allwinner's implementation (or rather something quite confusing). > > > > > > > > > > You're right that the lcd_rate and pll_rate seem to be generated from > > > > > the pixel clock, and it indeed looks like the ratio between the pixel > > > > > clock and the TCON dotclock is defined through the number of bits per > > > > > lanes. > > > > > > > > > > However, in this case, dsi_rate is actually the same than lcd_rate, > > > > > since pll_rate is going to be divided by dsi_div: > > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/disp_lcd.c#L791 > > > > > > > > > > Since lcd_div is 1, it also means that in this case, dsi_rate == > > > > > dclk_rate. > > > > > > > > > > The DSI module clock however, is always set to 148.5 MHz. Indeed, if > > > > > we look at: > > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/disp_lcd.c#L804 > > > > > > > > > > We can see that the rate in clk_info is used if it's different than > > > > > 0. This is filled by disp_al_lcd_get_clk_info, which, in the case of a > > > > > DSI panel, will hardcode it to 148.5 MHz: > > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/disp_al.c#L164 > > > > > > > > Let me explain, something more. > > > > > > > > According to bsp there are clk_info.tcon_div which I will explain below. > > > > clk_info.dsi_div which is dynamic and it depends on bpp/lanes, so it > > > > is 6 for 24bpp and 4 lanes devices. > > > > > > > > PLL rate here depends on dsi_div (not tcon_div) > > > > > > > > Code here > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/disp_lcd.c#L784 > > > > > > > > is computing the actual set rate, which depends on dsi_rate. > > > > > > > > lcd_rate = dclk_rate * clk_info.dsi_div; > > > > dsi_rate = pll_rate / clk_info.dsi_div; > > > > > > > > Say if the dclk_rate 148MHz then the dsi_rate is 888MHz which set rate > > > > for above link you mentioned. > > > > > > > > Here are the evidence with some prints. > > > > > > > > https://gist.github.com/openedev/9bae2d87d2fcc06b999fe48c998b7043 > > > > https://gist.github.com/openedev/700de2e3701b2bf3ad1aa0f0fa862c9a > > > > > > Ok, so we agree up to this point, and the prints confirm that the > > > analysis above is the right one. > > > > > > > > So, the DSI clock is set to this here: > > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/disp_lcd.c#L805 > > > > > > Your patch doesn't address that, so let's leave that one alone. > > > > Basically this is final pll set rate when sun4i_dotclock.c called the > > desired rate with ccu_nkm.c so it ended the final rate with parent as > > Line 8 of > > https://gist.github.com/openedev/700de2e3701b2bf3ad1aa0f0fa862c9a > > If that's important to the driver, it should be set explicitly then, > and not work by accident. > > > > > > The TCON *module* clock (the one in the clock controller) has been set > > > > > to lcd_rate (so the pixel clock times the number of bits per lane) here: > > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/disp_lcd.c#L800 > > > > > > > > > > And the PLL has been set to the same rate here: > > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/disp_lcd.c#L794 > > > > > > > > > > Let's take a step back now: that function we were looking at, > > > > > lcd_clk_config, is called by lcd_clk_enable, which is in turn called > > > > > by disp_lcd_enable here: > > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/disp_lcd.c#L1328 > > > > > > > > > > The next function being called is disp_al_lcd_cfg, and that function > > > > > will hardcode the TCON dotclock divider to 4, here: > > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/disp_al.c#L240 > > > > > > > > tcon_div from BSP point-of-view of there are two variants > > > > 00) clk_info.tcon_div which is 4 and same is set the divider position > > > > in SUN4I_TCON0_DCLK_REG (like above link refer) > > > > 01) tcon_div which is 4 and used for edge timings computation > > > > https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c#L12 > > > > > > > > The real reason for 01) is again 4 is they set the divider to 4 in 00) > > > > which is technically wrong because the dividers which used during > > > > dotclock in above (dsi_div) should be used here as well. Since there > > > > is no dynamic way of doing this BSP hard-coding these values. > > > > > > > > Patches 5,6,7 on this series doing this > > > > https://patchwork.freedesktop.org/series/60847/ > > > > > > > > Hope this explanation helps? > > > > > > It doesn't. > > > > > > The clock tree is this one: > > > > > > PLL(s) -> TCON module clock -> TCON dotclock. > > > > > > The links I mentioned above show that the clock set to lcd_rate is the > > > TCON module clocks (and it should be the one taking the bpp and lanes > > > into account), while the TCON dotclock uses a fixed divider of 4. > > > > Sorry, I can argue much other-than giving some code snips, according to [1] > > > > 00) Line 785, 786 with dclk_rate 148000000 > > > > lcd_rate = dclk_rate * clk_info.dsi_div; > > pll_rate = lcd_rate * clk_info.lcd_div; > > > > Since dsi_div is 6 (bpp/lanes), lcd_div 1 > > > > lcd_rate = 888000000, pll_rate = 888000000 > > > > 01) Line 801, 804 are final rates computed as per clock driver (say > > ccu_nkm in mainline) > > > > lcd_rate_set=891000000 > > > > As per your comments if it would be 4 then the desired numbers are > > would be 592000000 not 888000000. > > > > This is what I'm trying to say in all mails, and same as verified with > > 2-lanes devices as well where the dsi_div is 12 so the final rate is > > 290MHz * 12 > > In the code you sent, you're forcing a divider on the internal TCON > clock, while that one is fixed in the BSP. > > There's indeed the bpp / lanes divider, but it's used in the *parent* > clock of the one you're changing. > > And the dsi0_clk clock you pointed out in the code snippet is yet > another clock, the MIPI DSI module clock. Correct, look like I refereed wrong reference in the above mail. sorry for the noise. Actually I'm trying to explain about pll_rate here which indeed depends on dsi.div https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/disp_lcd.c#L786 lcd_rate = dclk_rate * clk_info.dsi_div; pll_rate = lcd_rate * clk_info.lcd_div; Say 1) For 148MHz dclk_rate with dsi_div is 6 (24/4) lcd_div is 1 which resulting pll_rate is 888MHz. 2) For 30MHz dclk_rate with 4 lane and 24 RGB the resulting pll_rate is 180MHz 3) For 27.5MHz dclk_rate with 2 lane and 24 RGB the resulting pll_rate is 330MHz Here is the few more logs in code, for case 2) [ 1.920441] sun4i_dclk_round_rate: min_div = 6 max_div = 6, rate = 30000000 [ 1.920505] ideal = 180000000, rounded = 178200000 [ 1.920509] sun4i_dclk_round_rate: div = 6 rate = 29700000 [ 1.920514] sun4i_dclk_round_rate: min_div = 6 max_div = 6, rate = 30000000 [ 1.920532] ideal = 180000000, rounded = 178200000 [ 1.920535] sun4i_dclk_round_rate: div = 6 rate = 29700000 [ 1.920572] sun4i_dclk_recalc_rate: val = 1, rate = 178200000 [ 1.920576] sun4i_dclk_recalc_rate: val = 1, rate = 178200000 [ 1.920597] rate = 178200000 [ 1.920599] parent_rate = 297000000 [ 1.920602] reg = 0x90c00000 [ 1.920605] _nkm.n = 3, nkm->n.offset = 0x1, nkm->n.shift = 8 [ 1.920609] _nkm.k = 2, nkm->k.offset = 0x1, nkm->k.shift = 4 [ 1.920612] _nkm.m = 10, nkm->m.offset = 0x1, nkm->m.shift = 0 [ 1.920958] sun4i_dclk_set_rate div 6 [ 1.920966] sun4i_dclk_recalc_rate: val = 6, rate = 29700000 and clk_summary: pll-video0 1 1 1 297000000 0 0 50000 hdmi 0 0 0 297000000 0 0 50000 tcon1 0 0 0 297000000 0 0 50000 pll-mipi 1 1 1 178200000 0 0 50000 tcon0 2 2 1 178200000 0 0 50000 tcon-pixel-clock 1 1 1 29700000 0 0 50000 pll-video0-2x 0 0 0 594000000 0 0 50000 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
