Message-ID: <cbb7866c-5e72-4656-966e-9c2244afedbd@gmail.com>
Date: Mon, 18 Dec 2023 13:49:52 +0100
From: Alex Bee <knaerzche@...il.com>
To: Maxime Ripard <mripard@...nel.org>
Cc: Sandy Huang <hjc@...k-chips.com>, Heiko Stübner
 <heiko@...ech.de>, Andy Yan <andyshrk@....com>,
 Rob Herring <robh+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Daniel Vetter <daniel@...ll.ch>, devicetree@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 19/27] drm/rockchip: inno_hdmi: Move tmds rate to
 connector state subclass


Am 18.12.23 um 11:06 schrieb Maxime Ripard:
> Hi,
>
> On Sat, Dec 16, 2023 at 05:26:30PM +0100, Alex Bee wrote:
>> Similar to the othter members of inno_hdmi_connector_state the tmds_rate is
>> not a property of the device, but of the connector state. Move it to
>> inno_hdmi_connector_state and make it a long to comply with the clock
>> framework. To get arround the issue of not having the connector state when
>> inno_hdmi_i2c_init is called in the bind path, getting the tmds rate is
>> wrapped in function which returns the fallback rate if the connector
>> doesn't have a state yet.
>>
>> Signed-off-by: Alex Bee <knaerzche@...il.com>
>> ---
>> changes in v2:
>>   - new patch
>>
>>   drivers/gpu/drm/rockchip/inno_hdmi.c | 36 +++++++++++++++++++---------
>>   1 file changed, 25 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/rockchip/inno_hdmi.c b/drivers/gpu/drm/rockchip/inno_hdmi.c
>> index f9bfae1e97a2..6799d24501b8 100644
>> --- a/drivers/gpu/drm/rockchip/inno_hdmi.c
>> +++ b/drivers/gpu/drm/rockchip/inno_hdmi.c
>> @@ -47,14 +47,13 @@ struct inno_hdmi {
>>   
>>   	struct inno_hdmi_i2c *i2c;
>>   	struct i2c_adapter *ddc;
>> -
>> -	unsigned int tmds_rate;
>>   };
>>   
>>   struct inno_hdmi_connector_state {
>>   	struct drm_connector_state	base;
>>   	unsigned int			enc_out_format;
>>   	unsigned int			colorimetry;
>> +	unsigned long			tmds_rate;
>>   };
>>   
>>   static struct inno_hdmi *encoder_to_inno_hdmi(struct drm_encoder *encoder)
>> @@ -133,11 +132,33 @@ static inline void hdmi_modb(struct inno_hdmi *hdmi, u16 offset,
>>   	hdmi_writeb(hdmi, offset, temp);
>>   }
>>   
>> +static unsigned long inno_hdmi_tmds_rate(struct inno_hdmi *hdmi)
>> +{
>> +	struct drm_connector *connector = &hdmi->connector;
>> +	struct drm_connector_state *conn_state =  connector->state;
>> +	struct inno_hdmi_connector_state *inno_conn_state;
>> +
>> +	if (conn_state) {
>> +		inno_conn_state = to_inno_hdmi_conn_state(conn_state);
>> +		return inno_conn_state->tmds_rate;
>> +	}
>> +
>> +	/*
>> +	 * When IP controller haven't configured to an accurate video
>> +	 * timing, then the TMDS clock source would be switched to
>> +	 * PCLK_HDMI, so we need to init the TMDS rate to PCLK rate,
>> +	 * and reconfigure the DDC clock.
>> +	 */
>> +
>> +	return clk_get_rate(hdmi->pclk);
>> +}
>> +
>>   static void inno_hdmi_i2c_init(struct inno_hdmi *hdmi)
>>   {
>>   	int ddc_bus_freq;
>> +	unsigned long tmds_rate = inno_hdmi_tmds_rate(hdmi);
>>   
>> -	ddc_bus_freq = (hdmi->tmds_rate >> 2) / HDMI_SCL_RATE;
>> +	ddc_bus_freq = (tmds_rate >> 2) / HDMI_SCL_RATE;
>>   
>>   	hdmi_writeb(hdmi, DDC_BUS_FREQ_L, ddc_bus_freq & 0xFF);
>>   	hdmi_writeb(hdmi, DDC_BUS_FREQ_H, (ddc_bus_freq >> 8) & 0xFF);
>> @@ -431,7 +452,7 @@ static int inno_hdmi_setup(struct inno_hdmi *hdmi,
>>   	 * DCLK_LCDC, so we need to init the TMDS rate to mode pixel
>>   	 * clock rate, and reconfigure the DDC clock.
>>   	 */
>> -	hdmi->tmds_rate = mode->clock * 1000;
>> +	inno_conn_state->tmds_rate = mode->clock * 1000;
>>   	inno_hdmi_i2c_init(hdmi);
>>   
>>   	/* Unmute video and audio output */
>> @@ -823,13 +844,6 @@ static int inno_hdmi_bind(struct device *dev, struct device *master,
>>   		goto err_disable_clk;
>>   	}
>>   
>> -	/*
>> -	 * When IP controller haven't configured to an accurate video
>> -	 * timing, then the TMDS clock source would be switched to
>> -	 * PCLK_HDMI, so we need to init the TMDS rate to PCLK rate,
>> -	 * and reconfigure the DDC clock.
>> -	 */
>> -	hdmi->tmds_rate = clk_get_rate(hdmi->pclk);
>>   	inno_hdmi_i2c_init(hdmi);
> I still think my patch is better there.
>
> There's two places that use the inno_hdmi.tmds_rate field: the two
> callers of inno_hdmi_i2c_init(). One is at bind time and needs to
> initialise it with a sane default since we don't have a mode set yet,
> the other is to update the internal clock rate while we have a mode set.
That’s, unfortunately, not fully true: inno_hdmi_set_pwr_mode not only
called at mode_set-time, but also in inno_hdmi_reset which is called in the
bind path (where we do not have a mode). That’s the point why I thought
extracting this in function makes sense. Otherwise I would have to pass the
tmds_rate to inno_hdmi_set_pwr_mode (also for the LOWER_PWR-case where I
don't need it) or do that whole fallback-if-no-mode thing in
inno_hdmi_set_pwr_mode directly. Neither would make the code easier to
follow. Being able to use it in inno_hdmi_i2c_init also is a nice gimmick.
I agree, having it in the custom connector state is not strictly required,
but I'd really like to keep the wrapping function.

Alex

> Since there's a single "modeset" user, there's no need to store it in
> the state structure at all: it can be a local variable.
>
> And in the bind function, you're not going to use the state structure
> either since there's no state, and it's just a default that has no
> relation to the modeset code at all.
>
> Your function on the other end tries to reconcile and handle the two.
> But there's no reason to, it just makes the code harder to follow. Just
> pass the parent rate you want to init with as an argument and it's easy
> to read and maintain.
>
> Maxime

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