On 8/27/20 6:49 PM, Stefan Wahren wrote:

Am 27.08.20 um 06:35 schrieb Hoegeun Kwon:

quoted

Hi Stefan,

Thank you for your review.


On 8/26/20 7:04 PM, Stefan Wahren wrote:

quoted

Hi Hoeguen,

Am 21.08.20 um 09:10 schrieb Hoegeun Kwon:

quoted

There is a problem that the output does not work at a resolution
exceeding FHD. To solve this, we need to adjust the bvb clock at a
resolution exceeding FHD.

this patch introduces a mandatory clock, please update
brcm,bcm2835-hdmi.yaml first.

Is this clock physically available on BCM283x or only on BCM2711?

As far as I know, BCM2711 raspberry pi 4 supports 4k,

don't supported on pi 3 and pi 3+.

Since 4k is not supported in versions prior to Raspberry Pi 4,

I don't think we need to modify the bvb clock.


So I think it is better to update 'brcm,bcm2711-hdmi.yaml'

instead of 'brcm,bcm2835-hdmi.yaml'.

You are correct please update only brcm,bcm2711-hdmi.yaml.

My concern was that the function vc4_hdmi_encoder_pre_crtc_configure()
is called on a non-bcm2711 platform or on a Raspberry Pi 4 with an older
DTB. So making the BVB clock optional might be better?

You are right, if use old dtb, we have a problem with the hdmi driver.

So how about modifying it like this?

@@ -1614,8 +1614,8 @@ static int vc5_hdmi_init_resources(struct vc4_hdmi 

*vc4_hdmi)

         vc4_hdmi->pixel_bvb_clock = devm_clk_get(dev, "bvb");
         if (IS_ERR(vc4_hdmi->pixel_bvb_clock)) {
-               DRM_ERROR("Failed to get pixel bvb clock\n");
-               return PTR_ERR(vc4_hdmi->pixel_bvb_clock);
+               DRM_WARN("Failed to get pixel bvb clock\n");
+               vc4_hdmi->pixel_bvb_clock = NULL;
         }

         vc4_hdmi->reset = devm_reset_control_get(dev, NULL);

If we modify like this, if there is no bvb clock in dtb, then 
pixel_bvb_clock will be null

and it will not affect the clk control function below.

   - clk_set_rate()
   - clk_prepare_enable()
   - clk_disable_unprepare()


Best regards

Hoegeun

quoted

Please comment, what do you think?

quoted

I'm a little bit afraid, this change could break with older firmware
versions on BCM283x.

Tested it several times with libdrm modetest.

I expect there will be no problem.


Best regards,

Hoegeun

quoted

Best regards
Stefan

quoted

Signed-off-by: Hoegeun Kwon <redacted>
---
   drivers/gpu/drm/vc4/vc4_hdmi.c | 25 +++++++++++++++++++++++++
   drivers/gpu/drm/vc4/vc4_hdmi.h |  1 +
   2 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 95ec5eedea39..eb3192d1fd86 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -80,6 +80,7 @@
   # define VC4_HD_M_ENABLE			BIT(0)
   
   #define CEC_CLOCK_FREQ 40000
+#define VC4_HSM_MID_CLOCK 149985000
   
   static int vc4_hdmi_debugfs_regs(struct seq_file *m, void *unused)
   {

@@ -380,6 +381,7 @@ static void vc4_hdmi_encoder_post_crtc_powerdown(struct drm_encoder *encoder)
   	HDMI_WRITE(HDMI_VID_CTL,
   		   HDMI_READ(HDMI_VID_CTL) & ~VC4_HD_VID_CTL_ENABLE);
   
+	clk_disable_unprepare(vc4_hdmi->pixel_bvb_clock);
   	clk_disable_unprepare(vc4_hdmi->hsm_clock);
   	clk_disable_unprepare(vc4_hdmi->pixel_clock);
   

@@ -638,6 +640,23 @@ static void vc4_hdmi_encoder_pre_crtc_configure(struct drm_encoder *encoder)
   		return;
   	}
   
+	ret = clk_set_rate(vc4_hdmi->pixel_bvb_clock,
+			(hsm_rate > VC4_HSM_MID_CLOCK ? 150000000 : 75000000));
+	if (ret) {
+		DRM_ERROR("Failed to set pixel bvb clock rate: %d\n", ret);
+		clk_disable_unprepare(vc4_hdmi->hsm_clock);
+		clk_disable_unprepare(vc4_hdmi->pixel_clock);
+		return;
+	}
+
+	ret = clk_prepare_enable(vc4_hdmi->pixel_bvb_clock);
+	if (ret) {
+		DRM_ERROR("Failed to turn on pixel bvb clock: %d\n", ret);
+		clk_disable_unprepare(vc4_hdmi->hsm_clock);
+		clk_disable_unprepare(vc4_hdmi->pixel_clock);
+		return;
+	}
+
   	if (vc4_hdmi->variant->reset)
   		vc4_hdmi->variant->reset(vc4_hdmi);
   

@@ -1593,6 +1612,12 @@ static int vc5_hdmi_init_resources(struct vc4_hdmi *vc4_hdmi)
   		return PTR_ERR(vc4_hdmi->audio_clock);
   	}
   
+	vc4_hdmi->pixel_bvb_clock = devm_clk_get(dev, "bvb");
+	if (IS_ERR(vc4_hdmi->pixel_bvb_clock)) {
+		DRM_ERROR("Failed to get pixel bvb clock\n");
+		return PTR_ERR(vc4_hdmi->pixel_bvb_clock);
+	}
+
   	vc4_hdmi->reset = devm_reset_control_get(dev, NULL);
   	if (IS_ERR(vc4_hdmi->reset)) {
   		DRM_ERROR("Failed to get HDMI reset line\n");

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
index 0806c6d9f24e..63c6f8bddf1d 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.h
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.h

@@ -147,6 +147,7 @@ struct vc4_hdmi {
   	struct clk *pixel_clock;
   	struct clk *hsm_clock;
   	struct clk *audio_clock;
+	struct clk *pixel_bvb_clock;
   
   	struct reset_control *reset;
   

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