Re: [PATCH v2 19/27] drm/rockchip: inno_hdmi: Move tmds rate to connector state subclass

[Alex Bee <knaerzche@xxxxxxxxx>]

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@xxxxxxxxx>
> > ---
> > 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