Am 27.08.20 um 06:35 schrieb Hoegeun Kwon:
> Hi Stefan,
>
> Thank you for your review.
>
>
> On 8/26/20 7:04 PM, Stefan Wahren wrote:
>> Hi Hoeguen,
>>
>> Am 21.08.20 um 09:10 schrieb Hoegeun Kwon:
>>> 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?
>
> Please comment, what do you think?
>
>> 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
>
>> Best regards
>> Stefan
>>
>>> Signed-off-by: Hoegeun Kwon <hoegeun.kwon@xxxxxxxxxxx>
>>> ---
>>> 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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