On 11.05.2022 17:47, Marek Vasut 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://protect2.fireeye.com/v1/url?k=fc60b660-9deba379-fc613d2f-74fe485cbfec-6741e6fb26af486e&q=1&e=07baacdb-540b-46fa-be0f-f534635150ec&u=https%3A%2F%2Fgithub.com%2Fmszyprow%2Flinux%2Ftree%2Fv5.18-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. https://lore.kernel.org/all/20220504114021.33265-1-jagan@xxxxxxxxxxxxxxxxxxxx/ Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
