Re: [PATCH 13/14] drm/bridge: synopsys: Add DW HDMI QP TX controller driver

Cristian Ciocaltea
2024-06-06T11:32:22Z

On 6/6/24 1:16 PM, Heiko Stübner wrote:
> Am Donnerstag, 6. Juni 2024, 11:53:23 CEST schrieb Cristian Ciocaltea:
>> On 6/5/24 5:48 PM, Heiko Stübner wrote:
>>> Am Samstag, 1. Juni 2024, 15:12:35 CEST schrieb Cristian Ciocaltea:
>>>> The Synopsys DesignWare HDMI 2.1 Quad-Pixel (QP) TX controller supports
>>>> the following features, among others:
>>>>
>>>> * Fixed Rate Link (FRL)
>>>> * 4K@120Hz and 8K@60Hz video modes
>>>> * Variable Refresh Rate (VRR) including Quick Media Switching (QMS), aka
>>>> Cinema VRR
>>>> * Fast Vactive (FVA), aka Quick Frame Transport (QFT)
>>>> * SCDC I2C DDC access
>>>> * TMDS Scrambler enabling 2160p@60Hz with RGB/YCbCr4:4:4
>>>> * YCbCr4:2:0 enabling 2160p@60Hz at lower HDMI link speeds
>>>> * Multi-stream audio
>>>> * Enhanced Audio Return Channel (EARC)
>>>>
>>>> Add driver to enable basic support, i.e. RGB output up to 4K@60Hz,
>>>> without audio, CEC or any HDMI 2.1 specific features.
>>>>
>>>> Co-developed-by: Algea Cao <algea.cao@rock-chips.com>
>>>> Signed-off-by: Algea Cao <algea.cao@rock-chips.com>
>>>> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
>>>> ---
>>>> drivers/gpu/drm/bridge/synopsys/Makefile | 2 +-
>>>> drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 787 +++++++++++++++++++++++++
>>>> drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.h | 831 +++++++++++++++++++++++++++
>>>> include/drm/bridge/dw_hdmi.h | 8 +
>>>> 4 files changed, 1627 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/bridge/synopsys/Makefile b/drivers/gpu/drm/bridge/synopsys/Makefile
>>>> index ce715562e9e5..8354e4879f70 100644
>>>> --- a/drivers/gpu/drm/bridge/synopsys/Makefile
>>>> +++ b/drivers/gpu/drm/bridge/synopsys/Makefile
>>>
>>>> +static int dw_hdmi_qp_i2c_read(struct dw_hdmi *hdmi,
>>>> + unsigned char *buf, unsigned int length)
>>>> +{
>>>> + struct dw_hdmi_i2c *i2c = hdmi->i2c;
>>>> + int stat;
>>>> +
>>>> + if (!i2c->is_regaddr) {
>>>> + dev_dbg(hdmi->dev, "set read register address to 0\n");
>>>> + i2c->slave_reg = 0x00;
>>>> + i2c->is_regaddr = true;
>>>> + }
>>>> +
>>>> + while (length--) {
>>>> + reinit_completion(&i2c->cmp);
>>>> +
>>>> + dw_hdmi_qp_mod(hdmi, i2c->slave_reg++ << 12, I2CM_ADDR,
>>>> + I2CM_INTERFACE_CONTROL0);
>>>> +
>>>> + dw_hdmi_qp_mod(hdmi, I2CM_FM_READ, I2CM_WR_MASK,
>>>> + I2CM_INTERFACE_CONTROL0);
>>>
>>> Somehow the segment handling is present in the rest of the i2c code here, but
>>> not the actual handling for reads.
>>>
>>> The vendor-kernel does:
>>>
>>> - dw_hdmi_qp_mod(hdmi, I2CM_FM_READ, I2CM_WR_MASK,
>>> - I2CM_INTERFACE_CONTROL0);
>>> + if (i2c->is_segment)
>>> + dw_hdmi_qp_mod(hdmi, I2CM_EXT_READ, I2CM_WR_MASK,
>>> + I2CM_INTERFACE_CONTROL0);
>>> + else
>>> + dw_hdmi_qp_mod(hdmi, I2CM_FM_READ, I2CM_WR_MASK,
>>> + I2CM_INTERFACE_CONTROL0);
>>
>> Hmm, for some reason this is not present in the stable-5.10-rock5 branch
>> I've been using as an implementation reference:
>>
>> https://github.com/radxa/kernel/blob/stable-5.10-rock5/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c#L760
>>
>> Is there an updated fork?
>
> I think the radxa code-base is quite old in terms of sdk-version it's based on.
> Grabbing a 6.1 branch from Radxa shows it in:
> https://github.com/radxa/kernel/blob/linux-6.1-stan-rkr1/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c#L995

Indeed, I should have switched to using this one as it seems to include
quite a few potentially interesting updates (will check in detail for v2).

For now, we miss cdc0984c90dc ("drm/bridge: synopsys: dw-hdmi-qp: Support
read ext block edid"), which provides an additional change:

@@ -1086,7 +1090,7 @@ static int dw_hdmi_i2c_xfer(struct i2c_adapter *adap,
i2c->is_segment = true;
hdmi_modb(hdmi, DDC_SEGMENT_ADDR, I2CM_SEG_ADDR,
I2CM_INTERFACE_CONTROL1);
- hdmi_modb(hdmi, *msgs[i].buf, I2CM_SEG_PTR,
+ hdmi_modb(hdmi, *msgs[i].buf << 7, I2CM_SEG_PTR,
I2CM_INTERFACE_CONTROL1);
} else {
if (msgs[i].flags & I2C_M_RD)

Will try to grab some more displays to improve testing on my end.

Thanks,
Cristian