Re: [U-Boot] [PATCH] sunxi: video: HDMI: Fix clock setup

On Sun, Mar 24, 2019 at 11:56 PM Jernej Skrabec jernej.skrabec@siol.net wrote:

Currently, HDMI driver doesn't consider minimum and maximum allowed rate of pll3 (video PLL). It works most of the time, but not always.

Consider monitor with resolution 1920x1200, which has pixel clock rate of 154 MHz. Current code would determine that pll3 rate has to be set to 154 MHz. However, minimum supported rate is 192 MHz. In this case video output just won't work.

I set the monitor with same resolution, but not sure with the pixel clock and unable to reproduce this with couple time. any specific usage case that the issue will reproduce ?

The reason why the driver is written in the way it is, is that at the time HDMI PHY and clock configuration wasn't fully understood. But now we have needed knowledge, so the issue can be fixed.

With this fix, clock configuration routine uses full range (1-16) for clock divider instead of limited one (1, 2, 4, 11). It also considers minimum and maximum allowed rate for pll3.

Fixes: 56009451d843 ("sunxi: video: Add A64/H3/H5 HDMI driver") Signed-off-by: Jernej Skrabec jernej.skrabec@siol.net

---

Hi!

Unfortunately, issue fixed with patch here has influence on Linux too. In Linux, minimum and maximum rate is considered only when changing rate. But because U-Boot already set PLL to "correct" value, Linux clock driver doesn't see the need to change it. I know that this is Linux driver issue but let's start at the source of the issue and fix it.

It would be very nice if this can go in 2019.04 release.

Best regards, Jernej

drivers/video/sunxi/sunxi_dw_hdmi.c | 62 +++++++++++++++++------------ 1 file changed, 37 insertions(+), 25 deletions(-)

diff --git a/drivers/video/sunxi/sunxi_dw_hdmi.c b/drivers/video/sunxi/sunxi_dw_hdmi.c index 9dbea649a0..6fe1aa7ee4 100644 --- a/drivers/video/sunxi/sunxi_dw_hdmi.c +++ b/drivers/video/sunxi/sunxi_dw_hdmi.c @@ -132,7 +132,7 @@ static int sunxi_dw_hdmi_wait_for_hpd(void) return -1; }

-static void sunxi_dw_hdmi_phy_set(uint clock) +static void sunxi_dw_hdmi_phy_set(uint clock, int phy_div) { struct sunxi_hdmi_phy * const phy = (struct sunxi_hdmi_phy *)(SUNXI_HDMI_BASE + HDMI_PHY_OFFS); @@ -146,7 +146,7 @@ static void sunxi_dw_hdmi_phy_set(uint clock) switch (div) { case 1: writel(0x30dc5fc0, &phy->pll);

•           writel(0x800863C0, &phy->clk);
  

•           writel(0x800863C0 | (phy_div - 1), &phy->clk);
            mdelay(10);
            writel(0x00000001, &phy->unk3);
            setbits_le32(&phy->pll, BIT(25));
  

@@ -164,7 +164,7 @@ static void sunxi_dw_hdmi_phy_set(uint clock) break; case 2: writel(0x39dc5040, &phy->pll);

•           writel(0x80084381, &phy->clk);
  

•           writel(0x80084380 | (phy_div - 1), &phy->clk);
            mdelay(10);
            writel(0x00000001, &phy->unk3);
            setbits_le32(&phy->pll, BIT(25));
  

@@ -178,7 +178,7 @@ static void sunxi_dw_hdmi_phy_set(uint clock) break; case 4: writel(0x39dc5040, &phy->pll);

•           writel(0x80084343, &phy->clk);
  

•           writel(0x80084340 | (phy_div - 1), &phy->clk);
            mdelay(10);
            writel(0x00000001, &phy->unk3);
            setbits_le32(&phy->pll, BIT(25));
  

@@ -192,7 +192,7 @@ static void sunxi_dw_hdmi_phy_set(uint clock) break; case 11: writel(0x39dc5040, &phy->pll);

•           writel(0x8008430a, &phy->clk);
  

•           writel(0x80084300 | (phy_div - 1), &phy->clk);
            mdelay(10);
            writel(0x00000001, &phy->unk3);
            setbits_le32(&phy->pll, BIT(25));
  

@@ -207,36 +207,46 @@ static void sunxi_dw_hdmi_phy_set(uint clock) } }

-static void sunxi_dw_hdmi_pll_set(uint clk_khz) +static void sunxi_dw_hdmi_pll_set(uint clk_khz, int *phy_div) {

•   int value, n, m, div = 0, diff;
  

•   int best_n = 0, best_m = 0, best_diff = 0x0FFFFFFF;
  

•   div = sunxi_dw_hdmi_get_divider(clk_khz * 1000);
  

•   int value, n, m, div, diff;
  

•   int best_n = 0, best_m = 0, best_div = 0, best_diff = 0x0FFFFFFF;
  
    /*
     * Find the lowest divider resulting in a matching clock. If there
     * is no match, pick the closest lower clock, as monitors tend to
     * not sync to higher frequencies.
     */
  

•   for (m = 1; m <= 16; m++) {
  

•           n = (m * div * clk_khz) / 24000;
  

•           if ((n >= 1) && (n <= 128)) {
  

•                   value = (24000 * n) / m / div;
  

•                   diff = clk_khz - value;
  

•                   if (diff < best_diff) {
  

•                           best_diff = diff;
  

•                           best_m = m;
  

•                           best_n = n;
  

•   for (div = 1; div <= 16; div++) {
  

•           int target = clk_khz * div;
  

•           if (target < 192000)
  

•                   continue;
  

•           if (target > 912000)
  

•                   continue;
  

I think this can be max allowed rate by PLL_VIDEO0 can't it be 1008 or 600 ?