Re: [PATCH v6 resend 2/5] phy: Add LVDS configuration options

From: Vinod Koul
Date: Wed Apr 13 2022 - 06:49:47 EST


On 13-04-22, 18:04, Liu Ying wrote:
> Hi Vinod,
>
> On Wed, 2022-04-13 at 11:41 +0530, Vinod Koul wrote:
> > On 02-04-22, 13:24, Liu Ying wrote:
> > > This patch allows LVDS PHYs to be configured through
> > > the generic functions and through a custom structure
> > > added to the generic union.
> > >
> > > The parameters added here are based on common LVDS PHY
> > > implementation practices. The set of parameters
> > > should cover all potential users.
> > >
> > > Cc: Kishon Vijay Abraham I <kishon@xxxxxx>
> > > Cc: Vinod Koul <vkoul@xxxxxxxxxx>
> > > Cc: NXP Linux Team <linux-imx@xxxxxxx>
> > > Signed-off-by: Liu Ying <victor.liu@xxxxxxx>
> > > ---
> > > v5->v6:
> > > * Rebase upon v5.17-rc1.
> > >
> > > v4->v5:
> > > * Align kernel-doc style to include/linux/phy/phy.h. (Vinod)
> > > * Trivial tweaks.
> > > * Drop Robert's R-b tag.
> > >
> > > v3->v4:
> > > * Add Robert's R-b tag.
> > >
> > > v2->v3:
> > > * No change.
> > >
> > > v1->v2:
> > > * No change.
> > >
> > > include/linux/phy/phy-lvds.h | 32 ++++++++++++++++++++++++++++++++
> > > include/linux/phy/phy.h | 4 ++++
> > > 2 files changed, 36 insertions(+)
> > > create mode 100644 include/linux/phy/phy-lvds.h
> > >
> > > diff --git a/include/linux/phy/phy-lvds.h b/include/linux/phy/phy-
> > > lvds.h
> > > new file mode 100644
> > > index 000000000000..7a2f4747f624
> > > --- /dev/null
> > > +++ b/include/linux/phy/phy-lvds.h
> > > @@ -0,0 +1,32 @@
> > > +/* SPDX-License-Identifier: GPL-2.0 */
> > > +/*
> > > + * Copyright 2020 NXP
> >
> > 2022 now
>
> I may change it to 'Copyright 2020,2022 NXP'.
>
> >
> > > + */
> > > +
> > > +#ifndef __PHY_LVDS_H_
> > > +#define __PHY_LVDS_H_
> > > +
> > > +/**
> > > + * struct phy_configure_opts_lvds - LVDS configuration set
> > > + * @bits_per_lane_and_dclk_cycle: Number of bits per data lane
> > > and
> > > + * differential clock cycle.
> >
> > What does it mean by bits per data lane and differential clock cycle?
>
> Please check Documentation/devicetree/bindings/display/panel/lvds.yaml.
> lvds.yaml metions slot. 'bits_per_lane_and_dclk_cycle' means the
> number of slots. But, I don't find the word 'slot' in my lvds relevant
> specs which mentioned in lvds.yaml, so 'slots' is probably not a
> generic name(lvds.yaml is for display panel). So, I use
> 'bits_per_lane_and_dclk_cycle' as the name tells what it means.

variable name is fine, explanation for bit per lane and differential
clock cycle didnt help, maybe add better explanation of what this
variable means

>
> >
> > > + * @differential_clk_rate: Clock rate, in Hertz, of the
> > > LVDS
> > > + * differential clock.
> > > + * @lanes: Number of active, consecutive,
> > > + * data lanes, starting from lane
> > > 0,
> > > + * used for the transmissions.
> > > + * @is_slave: Boolean, true if the
> > > phy is a slave
> > > + * which works together with a
> > > master
> > > + * phy to support dual link
> > > transmission,
> > > + * otherwise a regular phy or a
> > > master phy.
> > > + *
> > > + * This structure is used to represent the configuration state of
> > > a LVDS phy.
> > > + */
> > > +struct phy_configure_opts_lvds {
> > > + unsigned int bits_per_lane_and_dclk_cycle;
> > > + unsigned long differential_clk_rate;
> > > + unsigned int lanes;
> > > + bool is_slave;
> > > +};
> >
> > Where is the user of this new configuration? Can you post that patch
> > for
> > reference as well please
>
> Patch 5/5 uses it. Also, I posted two drm bridge drivers[1][2] which
> use it.

That is phy driver not the user
>
> [1]
> https://patchwork.kernel.org/project/dri-devel/patch/1617172405-12962-13-git-send-email-victor.liu@xxxxxxx/
> [2]
> https://patchwork.kernel.org/project/dri-devel/patch/1617172405-12962-14-git-send-email-victor.liu@xxxxxxx/

this is helpful, thanks

--
~Vinod