On Fri, Apr 05, 2024 at 07:54:46PM +0530, Vinod Koul wrote:
> On 06-03-24, 15:48, Maxime Ripard wrote:
> > Hi Alexander,
> >
> > On Wed, Mar 06, 2024 at 11:16:19AM +0100, Alexander Stein wrote:
> > > From: Sandor Yu <Sandor.yu@xxxxxxx>
> > >
> > > Allow HDMI PHYs to be configured through the generic
> > > functions through a custom structure added to the generic union.
> > >
> > > The parameters added here are based on HDMI PHY
> > > implementation practices. The current set of parameters
> > > should cover the potential users.
> > >
> > > Signed-off-by: Sandor Yu <Sandor.yu@xxxxxxx>
> > > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > > Acked-by: Vinod Koul <vkoul@xxxxxxxxxx>
> > > ---
> > > include/linux/phy/phy-hdmi.h | 24 ++++++++++++++++++++++++
> > > include/linux/phy/phy.h | 7 ++++++-
> > > 2 files changed, 30 insertions(+), 1 deletion(-)
> > > create mode 100644 include/linux/phy/phy-hdmi.h
> > >
> > > diff --git a/include/linux/phy/phy-hdmi.h b/include/linux/phy/phy-hdmi.h
> > > new file mode 100644
> > > index 0000000000000..b7de88e9090f0
> > > --- /dev/null
> > > +++ b/include/linux/phy/phy-hdmi.h
> > > @@ -0,0 +1,24 @@
> > > +/* SPDX-License-Identifier: GPL-2.0 */
> > > +/*
> > > + * Copyright 2022 NXP
> > > + */
> > > +
> > > +#ifndef __PHY_HDMI_H_
> > > +#define __PHY_HDMI_H_
> > > +
> > > +#include <linux/hdmi.h>
> > > +/**
> > > + * struct phy_configure_opts_hdmi - HDMI configuration set
> > > + * @pixel_clk_rate: Pixel clock of video modes in KHz.
> > > + * @bpc: Maximum bits per color channel.
> > > + * @color_space: Colorspace in enum hdmi_colorspace.
> > > + *
> > > + * This structure is used to represent the configuration state of a HDMI phy.
> > > + */
> > > +struct phy_configure_opts_hdmi {
> > > + unsigned int pixel_clk_rate;
> > > + unsigned int bpc;
> > > + enum hdmi_colorspace color_space;
> > > +};
> >
> > Does the PHY actually care about the pixel clock rate, color space and
> > formats, or does it only care about the character rate?
>
> Nope it should not
After taking a look at the Cadence PHY driver, I share the feeling that
hdptx_hdmi_feedback_factor() should be reworked into drm_display helper
and then the struct phy_configure_opts_hdmi can be limited to having a
single unsigned long char_freq or bit_rate field.
I'm not sure whether we need anything corresponding to the TMDS Bit
Clock Ratio control. As far as I understand, it can be deduced from the
Bit Rate.
--
With best wishes
Dmitry
