Re: [PATCH V2 0/3] DSI host and peripheral initialisation ordering

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, May 11, 2022 at 9:17 PM Marek Vasut <marex@xxxxxxx> wrote:
>
> On 5/11/22 16:58, Marek Szyprowski wrote:
> > Hi Dave,
> >
> > On 05.04.2022 13:43, Dave Stevenson wrote:
> >> On Fri, 18 Mar 2022 at 12:25, Dave Stevenson
> >> <dave.stevenson@xxxxxxxxxxxxxxx>  wrote:
> >>> On Fri, 4 Mar 2022 at 15:18, Dave Stevenson
> >>> <dave.stevenson@xxxxxxxxxxxxxxx>  wrote:
> >>>> Hi All
> >>> A gentle ping on this series. Any comments on the approach?
> >>> Thanks.
> >> I realise the merge window has just closed and therefore folks have
> >> been busy, but no responses on this after a month?
> >>
> >> Do I give up and submit a patch to document that DSI is broken and no one cares?
> >
> > Thanks for pointing this patchset in the 'drm: bridge: Add Samsung MIPI
> > DSIM bridge' thread, otherwise I would miss it since I'm not involved
> > much in the DRM development.
> >
> > This resolves most of the issues in the Exynos DSI and its recent
> > conversion to the drm bridge framework. I've added the needed
> > prepare_upstream_first flags to the panels and everything works fine
> > without the bridge chain order hacks.
> >
> > Feel free to add:
> >
> > Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> >
> >
> > The only remaining thing to resolve is the moment of enabling DSI host.
> > The proper sequence is:
> >
> > 1. host power on, 2. device power on, 3. host init, 4. device init, 5.
> > video enable.
>
> +CC Raphael, STM32MP1 has similar topic.
>
> > #1 is done in dsi's pre_enable, #2 is done in panel's prepare. #3 was so
> > far done in the first host transfer call, which usually happens in
> > panel's prepare, then the #4 happens. Then video enable is done in the
> > enable callbacks.
> >
> > Jagan wants to move it to the dsi host pre_enable() to let it work with
> > DSI bridges controlled over different interfaces
> > (https://lore.kernel.org/all/20220504114021.33265-6-jagan@xxxxxxxxxxxxxxxxxxxx/
> > ). This however fails on Exynos with DSI panels, because when dsi's
> > pre_enable is called, the dsi device is not yet powered. I've discussed
> > this with Andrzej Hajda and we came to the conclusion that this can be
> > resolved by adding the init() callback to the struct mipi_dsi_host_ops.
> > Then DSI client (next bridge or panel) would call it after powering self
> > on, but before sending any DSI commands in its pre_enable/prepare functions.
> >
> > I've prepared a prototype of such solution. This approach finally
> > resolved all the initialization issues! The bridge chain finally matches
> > the hardware, no hack are needed, and everything is controlled by the
> > DRM core. This prototype also includes the Jagan's patches, which add
> > IMX support to Samsung DSIM. If one is interested, here is my git repo
> > with all the PoC patches:
> >
> > https://github.com/mszyprow/linux/tree/v5.18-next-20220511-dsi-rework
>
> Can you CC me on the iMX DSIM discussion/patches ? It seems I was left
> out of it all, even though I work with the iMX8M DRM stuff extensively.

Sorry, this is not intentional. I added you and many others in RFC and
subsequently, I have added in the next versions whoever responds to
the previous. I will do it in the next version DSIM.

Thanks,
Jagan.



[Index of Archives]     [Linux DRI Users]     [Linux Intel Graphics]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux