Re: [PATCH 2/3] drm/msm/dsi: support DSC configurations with slice_per_pkt > 1

[Alexander Koskovich]

On Mon, Oct 13, 2025 at 05:34:06PM +0300, Dmitry Baryshkov wrote:
> On Mon, Oct 13, 2025 at 09:17:04PM +0800, Junjie Cao wrote:
> > Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx> 于2025年10月13日周一 20:31写道：
> > > On Mon, Oct 13, 2025 at 07:04:43PM +0800, Junjie Cao wrote:
> > > > Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx> 于2025年10月13日周一 17:39写道：
> > > > > On 13/10/2025 04:52, 曹俊杰 wrote:
> > > > > >  >Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx
> > > > > > <mailto:dmitry.baryshkov@xxxxxxxxxxxxxxxx>> 于2025年10月2日周四 10:04写道：
> > > > > >  >On Wed, Oct 01, 2025 at 09:59:13PM +0800, Junjie Cao wrote:
> > > > > >  >> From: Jun Nie <jun.nie@xxxxxxxxxx <mailto:jun.nie@xxxxxxxxxx>>
> > > > > >  >>
> > > > > >  >> Some panels support multiple slice to be sent in a single DSC
> > > > > > packet. And
> > > > > >  >> this feature is a must for specific panels, such as JDI LPM026M648C.
> > > > > > Add a
> > > > > >  >> dsc_slice_per_pkt member into struct mipi_dsi_device and support the
> > > > > >  >> feature in msm mdss driver.
> > > > > >  >>
> > > > > >  >> Co-developed-by: Jonathan Marek <jonathan@xxxxxxxx
> > > > > > <mailto:jonathan@xxxxxxxx>>
> > > > > >  >> Signed-off-by: Jonathan Marek <jonathan@xxxxxxxx
> > > > > > <mailto:jonathan@xxxxxxxx>>
> > > > > >  >> Signed-off-by: Jun Nie <jun.nie@xxxxxxxxxx <mailto:jun.nie@xxxxxxxxxx>>
> > > > > >  >> Signed-off-by: Junjie Cao <caojunjie650@xxxxxxxxx
> > > > > > <mailto:caojunjie650@xxxxxxxxx>>
> > > > > >  >> ---
> > > > > >  >>  drivers/gpu/drm/msm/dsi/dsi_host.c | 25 ++++++++++---------------
> > > > > >  >>  include/drm/drm_mipi_dsi.h         |  2 ++
> > > > > >  >>  2 files changed, 12 insertions(+), 15 deletions(-)
> > > > > >  >
> > > > > >  >Please extract the generic part, so that it can be merged through a
> > > > > >  >generic tree.
> > > > > >  >
> > > > > >
> > > > > > Sorry, I don't get it.  The generic part, generic tree? Do you mean
> > > > > > the drm tree? `slice_per_pkt >= 2` is seen on the panels of these
> > > > > > tablets that are equipped with qcom chips. I don't know if these
> > > > > > panels are used on other platforms, and if it is necessary to do it
> > > > > > in drm.
> > > > >
> > > > > There are two changes here:
> > > > > - MIPI DSI header change
> > > > > - msm DSI driver
> > > > >
> > > > > I've asked to split it to those two commits so that he change for
> > > > > drm_mipi_dsi.h is more obvious for reviewers and so that it can be
> > > > > merged through a drm-misc tree (or through drm-msm tree provided it gets
> > > > > a necessary ack).
> > > > >
> > > >
> > > > Thanks for your clear explanation.
> > > >
> > > > I don't mind to add the field separately. But should I submit it
> > > > with the panel driver together? Otherwise, this field is unused
> > > > for a while.
> > > >
> > > > However, as you mentioned, this is not a part of standard, neither
> > > > mipi dsi nor VESA DSC. Recently, only Qualcomm devices require it
> > > > to calculate parameters, then we use them to program registers. Why
> > > > don't we parse the field from devicetree?
> > >
> > > Because the value is uniquelly identified by the panel's compat string.
> > >
> > 
> > Yes, it is panel specified.
> > But can we set it for every panel like
> > 
> > &mdss_dsi0 {
> >     qcom,mdss-dsc-slice-per-pkt = <2>;
> > 
> >     status = "okay";
> > 
> >     panel: panel@0 {
> >         compatible = "foo,bar";
> >         reg = <0>;
> >     };
> > };
> > 
> > or moving the property to panel node? We access it from child node.
> 
> Why do you need it in DT if the panel driver can provide this
> information.

Hello, I need this patch for the Tianma TA066VVHM03 on the ASUS ROG Phone 3. Is
the only change required at this point to split the generic part, and is a v2
in the works to address this?

> 
> -- 
> With best wishes
> Dmitry

Thanks,
Alex