Re: [PATCH] drm: rcar_lvds: Fix dual link mode operations
Hi Laurent,
On Thu, Aug 01, 2019 at 06:11:29PM +0300, Laurent Pinchart wrote:
> Hello Jacopo,
>
> Thank you for the patch.
>
> On Tue, Jul 23, 2019 at 06:57:00PM +0200, Jacopo Mondi wrote:
> > The R-Car LVDS encoder units support dual-link operations by splitting
> > the pixel output between the primary encoder and the companion one.
>
> s/the companion one/its companion/
>
> >
> > In order for the primary encoder to succesfully control the companion's
> > operations this should not fail at probe time and register itself its
> > associated drm bridge so that the primary one can find it.
>
> This is hard to parse.
>
Re-reading the whole commit message, I would actually drop it
completely, it's enough what we have here below.
> > Currently the companion encoder fails at probe time, causing the
> > registration of the primary to fail preventing the whole DU unit to be
> > registered correctly.
> >
> > Fixes: fa440d870358 ("drm: rcar-du: lvds: Add support for dual-link mode")
> > Reported-by: Fabrizio Castro
> > Signed-off-by: Jacopo Mondi
> >
> > ---
> > The "Fixes" tag refers to a patch currently part of the
> > renesas-drivers-2019-07-09-v5.2 branch of Geert's renesas-drivers tree.
> >
> > drivers/gpu/drm/rcar-du/rcar_lvds.c | 31 +
> > 1 file changed, 23 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > index bada7ee98544..8b015ba95895 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > @@ -767,14 +767,29 @@ static int rcar_lvds_parse_dt(struct rcar_lvds *lvds)
> > of_node_put(remote_input);
> > of_node_put(remote);
> >
> > - /*
> > -* On D3/E3 the LVDS encoder provides a clock to the DU, which can be
> > -* used for the DPAD output even when the LVDS output is not connected.
> > -* Don't fail probe in that case as the DU will need the bridge to
> > -* control the clock.
> > -*/
> > - if (lvds->info->quirks & RCAR_LVDS_QUIRK_EXT_PLL)
> > - return ret == -ENODEV ? 0 : ret;
> > + switch (ret) {
> > + case -ENODEV:
> > + /*
> > +* On D3/E3 the LVDS encoder provides a clock to the DU, which
> > +* can be used for the DPAD output even when the LVDS output is
> > +* not connected. Don't fail probe in that case as the DU will
> > +* need the bridge to control the clock.
> > +*/
> > + if (lvds->info->quirks & RCAR_LVDS_QUIRK_EXT_PLL)
> > + ret = 0;
> > + break;
> > + case -ENXIO:
> > + /*
> > +* When the LVDS output is used in dual link mode, the
> > +* companion encoder fails at
> > +* 'rcar_lvds_parse_dt_companion()'. Don't fail probe in
> > +* that case as the master encoder will need the companion's
> > +* bridge to control its operations.
> > +*/
> > + if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK)
> > + ret = 0;
>
> As -ENXIO can only be returned by rcar_lvds_parse_dt_companion(), and
> rcar_lvds_parse_dt_companion() is only called when the
> RCAR_LVDS_QUIRK_DUAL_LINK flag is set, this essentially means that you
> always zero the error returned from rcar_lvds_parse_dt_companion(). This
Not totally correct, as rcar_lvds_parse_dt_companion() might also
return EPROBE_DEFER, but...
> is both complicated and too drastic as the second -ENXIO error case
> shouldn't be ignored. It would be better and simpler to return 0 from
> rcar_lvds_parse_dt_companion() when the renesas,companion property can't
> be found.
I agree, returning 0 when when the property is not specified is enough
and much simpler. I got dragged away by the idea of centralizing error
handling at the end of the function, but it's ugly and also wrongly
zeroes the second -ENXIO error returned by the parse_companion
function.
I'll change to what you suggested!
Thanks
j
>
> > + break;
> > + }
> >
> > return ret;
> > }
>
> --
> Regards,
>
> Laurent Pinchart
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Re: [PATCH] drm: rcar_lvds: Fix dual link mode operations
Hello Jacopo,
Thank you for the patch.
On Tue, Jul 23, 2019 at 06:57:00PM +0200, Jacopo Mondi wrote:
> The R-Car LVDS encoder units support dual-link operations by splitting
> the pixel output between the primary encoder and the companion one.
s/the companion one/its companion/
>
> In order for the primary encoder to succesfully control the companion's
> operations this should not fail at probe time and register itself its
> associated drm bridge so that the primary one can find it.
This is hard to parse.
> Currently the companion encoder fails at probe time, causing the
> registration of the primary to fail preventing the whole DU unit to be
> registered correctly.
>
> Fixes: fa440d870358 ("drm: rcar-du: lvds: Add support for dual-link mode")
> Reported-by: Fabrizio Castro
> Signed-off-by: Jacopo Mondi
>
> ---
> The "Fixes" tag refers to a patch currently part of the
> renesas-drivers-2019-07-09-v5.2 branch of Geert's renesas-drivers tree.
>
> drivers/gpu/drm/rcar-du/rcar_lvds.c | 31 +
> 1 file changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> index bada7ee98544..8b015ba95895 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> @@ -767,14 +767,29 @@ static int rcar_lvds_parse_dt(struct rcar_lvds *lvds)
> of_node_put(remote_input);
> of_node_put(remote);
>
> - /*
> - * On D3/E3 the LVDS encoder provides a clock to the DU, which can be
> - * used for the DPAD output even when the LVDS output is not connected.
> - * Don't fail probe in that case as the DU will need the bridge to
> - * control the clock.
> - */
> - if (lvds->info->quirks & RCAR_LVDS_QUIRK_EXT_PLL)
> - return ret == -ENODEV ? 0 : ret;
> + switch (ret) {
> + case -ENODEV:
> + /*
> + * On D3/E3 the LVDS encoder provides a clock to the DU, which
> + * can be used for the DPAD output even when the LVDS output is
> + * not connected. Don't fail probe in that case as the DU will
> + * need the bridge to control the clock.
> + */
> + if (lvds->info->quirks & RCAR_LVDS_QUIRK_EXT_PLL)
> + ret = 0;
> + break;
> + case -ENXIO:
> + /*
> + * When the LVDS output is used in dual link mode, the
> + * companion encoder fails at
> + * 'rcar_lvds_parse_dt_companion()'. Don't fail probe in
> + * that case as the master encoder will need the companion's
> + * bridge to control its operations.
> + */
> + if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK)
> + ret = 0;
As -ENXIO can only be returned by rcar_lvds_parse_dt_companion(), and
rcar_lvds_parse_dt_companion() is only called when the
RCAR_LVDS_QUIRK_DUAL_LINK flag is set, this essentially means that you
always zero the error returned from rcar_lvds_parse_dt_companion(). This
is both complicated and too drastic as the second -ENXIO error case
shouldn't be ignored. It would be better and simpler to return 0 from
rcar_lvds_parse_dt_companion() when the renesas,companion property can't
be found.
> + break;
> + }
>
> return ret;
> }
--
Regards,
Laurent Pinchart
Re: [PATCH] drm: rcar_lvds: Fix dual link mode operations
Hi Geert,
On Wed, Jul 24, 2019 at 09:28:58AM +0200, Geert Uytterhoeven wrote:
> Hi Jacopo,
>
> On Wed, Jul 24, 2019 at 3:38 AM Jacopo Mondi
> wrote:
> > The R-Car LVDS encoder units support dual-link operations by splitting
> > the pixel output between the primary encoder and the companion one.
> >
> > In order for the primary encoder to succesfully control the companion's
> > operations this should not fail at probe time and register itself its
> > associated drm bridge so that the primary one can find it.
> >
> > Currently the companion encoder fails at probe time, causing the
> > registration of the primary to fail preventing the whole DU unit to be
> > registered correctly.
> >
> > Fixes: fa440d870358 ("drm: rcar-du: lvds: Add support for dual-link mode")
> > Reported-by: Fabrizio Castro
> > Signed-off-by: Jacopo Mondi
> >
> > ---
> > The "Fixes" tag refers to a patch currently part of the
> > renesas-drivers-2019-07-09-v5.2 branch of Geert's renesas-drivers tree.
>
> The broken commit is also present in v5.3-rc1.
You're right... This is then entitled to be collected for rc2 then.
Thanks
j
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 --
> ge...@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like
> that.
> -- Linus Torvalds
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RE: [PATCH] drm: rcar_lvds: Fix dual link mode operations
Hi Jacopo,
Thank you for your patch!
> From: linux-renesas-soc-ow...@vger.kernel.org
> On Behalf Of Jacopo Mondi
> Sent: 23 July 2019 17:57
> Subject: [PATCH] drm: rcar_lvds: Fix dual link mode operations
>
> The R-Car LVDS encoder units support dual-link operations by splitting
> the pixel output between the primary encoder and the companion one.
>
> In order for the primary encoder to succesfully control the companion's
> operations this should not fail at probe time and register itself its
> associated drm bridge so that the primary one can find it.
>
> Currently the companion encoder fails at probe time, causing the
> registration of the primary to fail preventing the whole DU unit to be
> registered correctly.
>
> Fixes: fa440d870358 ("drm: rcar-du: lvds: Add support for dual-link mode")
> Reported-by: Fabrizio Castro
> Signed-off-by: Jacopo Mondi
Reviewed-by: Fabrizio Castro
Tested-by: Fabrizio Castro
>
> ---
> The "Fixes" tag refers to a patch currently part of the
> renesas-drivers-2019-07-09-v5.2 branch of Geert's renesas-drivers tree.
>
> drivers/gpu/drm/rcar-du/rcar_lvds.c | 31 +
> 1 file changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> index bada7ee98544..8b015ba95895 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> @@ -767,14 +767,29 @@ static int rcar_lvds_parse_dt(struct rcar_lvds *lvds)
> of_node_put(remote_input);
> of_node_put(remote);
>
> - /*
> - * On D3/E3 the LVDS encoder provides a clock to the DU, which can be
> - * used for the DPAD output even when the LVDS output is not connected.
> - * Don't fail probe in that case as the DU will need the bridge to
> - * control the clock.
> - */
> - if (lvds->info->quirks & RCAR_LVDS_QUIRK_EXT_PLL)
> - return ret == -ENODEV ? 0 : ret;
> + switch (ret) {
> + case -ENODEV:
> + /*
> + * On D3/E3 the LVDS encoder provides a clock to the DU, which
> + * can be used for the DPAD output even when the LVDS output is
> + * not connected. Don't fail probe in that case as the DU will
> + * need the bridge to control the clock.
> + */
> + if (lvds->info->quirks & RCAR_LVDS_QUIRK_EXT_PLL)
> + ret = 0;
> + break;
> + case -ENXIO:
> + /*
> + * When the LVDS output is used in dual link mode, the
> + * companion encoder fails at
> + * 'rcar_lvds_parse_dt_companion()'. Don't fail probe in
> + * that case as the master encoder will need the companion's
> + * bridge to control its operations.
> + */
> + if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK)
> + ret = 0;
> + break;
> + }
>
> return ret;
> }
> --
> 2.22.0
Re: [PATCH] drm: rcar_lvds: Fix dual link mode operations
Hi Jacopo,
On Wed, Jul 24, 2019 at 3:38 AM Jacopo Mondi wrote:
> The R-Car LVDS encoder units support dual-link operations by splitting
> the pixel output between the primary encoder and the companion one.
>
> In order for the primary encoder to succesfully control the companion's
> operations this should not fail at probe time and register itself its
> associated drm bridge so that the primary one can find it.
>
> Currently the companion encoder fails at probe time, causing the
> registration of the primary to fail preventing the whole DU unit to be
> registered correctly.
>
> Fixes: fa440d870358 ("drm: rcar-du: lvds: Add support for dual-link mode")
> Reported-by: Fabrizio Castro
> Signed-off-by: Jacopo Mondi
>
> ---
> The "Fixes" tag refers to a patch currently part of the
> renesas-drivers-2019-07-09-v5.2 branch of Geert's renesas-drivers tree.
The broken commit is also present in v5.3-rc1.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
