From: Hoegeun Kwon <hoegeun.kwon@samsung.com>
To: Stefan Wahren <stefan.wahren@i2se.com>,
nsaenzjulienne@suse.de, eric@anholt.net, maxime@cerno.tech
Cc: devicetree@vger.kernel.org, tim.gover@raspberrypi.com,
dave.stevenson@raspberrypi.com, sboyd@kernel.org,
mturquette@baylibre.com, kdasu.kdev@gmail.com,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-clk@vger.kernel.org, robh+dt@kernel.org,
bcm-kernel-feedback-list@broadcom.com,
linux-rpi-kernel@lists.infradead.org, phil@raspberrypi.com,
linux-arm-kernel@lists.infradead.org,
Hoegeun Kwon <hoegeun.kwon@samsung.com>
Subject: Re: [PATCH 3/3] drm/vc4: hdmi: Add pixel bvb clock control
Date: Fri, 28 Aug 2020 15:30:04 +0900 [thread overview]
Message-ID: <a19de8d5-2b01-cb62-38a2-b0732068025c@samsung.com> (raw)
In-Reply-To: <84c423e8-25a6-8f23-cc80-7a17ce03fd1d@i2se.com>
On 8/27/20 6:49 PM, Stefan Wahren wrote:
> 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?
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
>
>> 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@samsung.com>
>>>> ---
>>>> 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;
>>>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
next prev parent reply other threads:[~2020-08-28 6:30 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200821071121epcas1p12225cf2891c2bbe22b90ac65e826dcaa@epcas1p1.samsung.com>
2020-08-21 7:10 ` [PATCH 0/3] drm/vc4: Support HDMI QHD or higher output Hoegeun Kwon
[not found] ` <CGME20200821071121epcas1p20c13a4116d56072293b1d81d8e253218@epcas1p2.samsung.com>
2020-08-21 7:10 ` [PATCH 1/3] clk: bcm: rpi: Add register to control pixel bvb clk Hoegeun Kwon
[not found] ` <CGME20200821071122epcas1p1069b0f2dd06ddff3bd5474dbec227684@epcas1p1.samsung.com>
2020-08-21 7:10 ` [PATCH 2/3] ARM: dts: bcm2711: Add bvb clock for hdmi-pixel Hoegeun Kwon
[not found] ` <CGME20200821071122epcas1p3d00dda4665f94192ac5e9ee829d0557d@epcas1p3.samsung.com>
2020-08-21 7:10 ` [PATCH 3/3] drm/vc4: hdmi: Add pixel bvb clock control Hoegeun Kwon
2020-08-26 10:04 ` Stefan Wahren
2020-08-27 4:35 ` Hoegeun Kwon
2020-08-27 9:49 ` Stefan Wahren
2020-08-28 6:30 ` Hoegeun Kwon [this message]
2020-08-28 12:45 ` Stefan Wahren
2020-08-28 15:25 ` Maxime Ripard
2020-08-28 15:37 ` Dave Stevenson
2020-09-01 2:07 ` Hoegeun Kwon
2020-08-28 19:10 ` Stefan Wahren
2020-08-28 9:11 ` Maxime Ripard
2020-08-28 9:22 ` Dave Stevenson
2020-08-26 9:56 ` [PATCH 0/3] drm/vc4: Support HDMI QHD or higher output Stefan Wahren
2020-08-28 9:44 ` Maxime Ripard
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