On Thu, Jul 13, 2023 at 3:01 AM Frieder Schrempf <frieder.schrempf@xxxxxxxxxx> wrote: > > Hi Tim, > > On 13.07.23 09:18, Frieder Schrempf wrote: > > Hi Tim, > > > > On 13.07.23 00:34, Tim Harvey wrote: > >> On Wed, May 3, 2023 at 9:33 AM Frieder Schrempf <frieder@xxxxxxx> wrote: > >>> > >>> From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx> > >>> > >>> According to the documentation [1] the proper enable flow is: > >>> > >>> 1. Enable DSI link and keep data lanes in LP-11 (stop state) > >>> 2. Disable stop state to bring data lanes into HS mode > >>> > >>> Currently we do this all at once within enable(), which doesn't > >>> allow to meet the requirements of some downstream bridges. > >>> > >>> To fix this we now enable the DSI in pre_enable() and force it > >>> into stop state using the FORCE_STOP_STATE bit in the ESCMODE > >>> register until enable() is called where we reset the bit. > >>> > >>> We currently do this only for i.MX8M as Exynos uses a different > >>> init flow where samsung_dsim_init() is called from > >>> samsung_dsim_host_transfer(). > >>> > >>> [1] https://docs.kernel.org/gpu/drm-kms-helpers.html#mipi-dsi-bridge-operation > >>> > >>> Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx> > >>> --- > >>> Changes for v2: > >>> * Drop RFC > >>> --- > >>> drivers/gpu/drm/bridge/samsung-dsim.c | 25 +++++++++++++++++++++++-- > >>> 1 file changed, 23 insertions(+), 2 deletions(-) > >>> > >>> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c > >>> index e0a402a85787..9775779721d9 100644 > >>> --- a/drivers/gpu/drm/bridge/samsung-dsim.c > >>> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c > >>> @@ -859,6 +859,10 @@ static int samsung_dsim_init_link(struct samsung_dsim *dsi) > >>> reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG); > >>> reg &= ~DSIM_STOP_STATE_CNT_MASK; > >>> reg |= DSIM_STOP_STATE_CNT(driver_data->reg_values[STOP_STATE_CNT]); > >>> + > >>> + if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) > >>> + reg |= DSIM_FORCE_STOP_STATE; > >>> + > >>> samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg); > >>> > >>> reg = DSIM_BTA_TIMEOUT(0xff) | DSIM_LPDR_TIMEOUT(0xffff); > >>> @@ -1340,6 +1344,9 @@ static void samsung_dsim_atomic_pre_enable(struct drm_bridge *bridge, > >>> ret = samsung_dsim_init(dsi); > >>> if (ret) > >>> return; > >>> + > >>> + samsung_dsim_set_display_mode(dsi); > >>> + samsung_dsim_set_display_enable(dsi, true); > >>> } > >>> } > >>> > >>> @@ -1347,9 +1354,16 @@ static void samsung_dsim_atomic_enable(struct drm_bridge *bridge, > >>> struct drm_bridge_state *old_bridge_state) > >>> { > >>> struct samsung_dsim *dsi = bridge_to_dsi(bridge); > >>> + u32 reg; > >>> > >>> - samsung_dsim_set_display_mode(dsi); > >>> - samsung_dsim_set_display_enable(dsi, true); > >>> + if (samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) { > >>> + samsung_dsim_set_display_mode(dsi); > >>> + samsung_dsim_set_display_enable(dsi, true); > >>> + } else { > >>> + reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG); > >>> + reg &= ~DSIM_FORCE_STOP_STATE; > >>> + samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg); > >>> + } > >>> > >>> dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE; > >>> } > >>> @@ -1358,10 +1372,17 @@ static void samsung_dsim_atomic_disable(struct drm_bridge *bridge, > >>> struct drm_bridge_state *old_bridge_state) > >>> { > >>> struct samsung_dsim *dsi = bridge_to_dsi(bridge); > >>> + u32 reg; > >>> > >>> if (!(dsi->state & DSIM_STATE_ENABLED)) > >>> return; > >>> > >>> + if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) { > >>> + reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG); > >>> + reg |= DSIM_FORCE_STOP_STATE; > >>> + samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg); > >>> + } > >>> + > >>> dsi->state &= ~DSIM_STATE_VIDOUT_AVAILABLE; > >>> } > >>> > >>> -- > >>> 2.40.0 > >>> > >> > >> Hi Frieder, > >> > >> I found this patch to break mipi-dsi display on my board which has: > >> - FocalTech FT5406 10pt touch controller (with no interrupt) > >> - Powertip PH800480T013-IDF02 compatible panel > >> - Toshiba TC358762 compatible DSI to DBI bridge > >> - ATTINY based regulator used for backlight controller and panel enable > >> > >> I enable this via a dt overlay in a pending patch > >> imx8mm-venice-gw72xx-0x-rpidsi.dtso [1] which works on 6.4 but not > >> 6.5-rc1 which has this patch. > >> > >> The issue appears as: > >> [ 6.110585] samsung-dsim 32e60000.dsi: xfer timed out: 29 06 00 00 > >> 64 01 05 00 00 00 > >> [ 6.326588] tc358762 32e60000.dsi.0: error initializing bridge (-110) > >> > >> Instead of > >> [ 1.011729] samsung-dsim 32e10000.dsi: supply vddcore not found, > >> using dummy regulator > >> [ 1.019829] samsung-dsim 32e10000.dsi: supply vddio not found, > >> using dummy regulator > >> [ 5.649928] samsung-dsim 32e10000.dsi: > >> [drm:samsung_dsim_host_attach] Attached tc358762 device > >> > >> I'm curious what board/panel were you needing this for and do you have > >> any ideas why it broke my setup? > >> > >> I'm also curious what board/panel Alexander tested this with and if > >> Adam or Jagan (or others) have tested this with their hardware? > > > > Sorry for breaking your setup. My test- and use-case is the same as > > Alexander's. I have the SN65DSI84 downstream bridge and without this > > patch it fails to come up in some cases. > > > > The failure is probably related to your downstream bridge being > > controlled by the DSI itself using command mode. The SN65DSI84 is > > instead controlled via I2C. > > > > Actually we should have tested this with a bridge that uses command mode > > before merging, now that I think of it. But I wasn't really aware of > > this until now. > > > > I'll have a closer look at the issue and then will get back to you. In > > the meantime if anyone can help analyze the problem or has proposals how > > to fix it, please let us know. > > With my patch samsung_dsim_init() now initializes the DSIM to stop > state. When being called from samsung_dsim_atomic_pre_enable() this > works as the stop state is cleared later in samsung_dsim_atomic_enable(). > > When being called from samsung_dsim_host_transfer() to handle transfers > before samsung_dsim_atomic_pre_enable() was called, the stop state is > never cleared and transfers will fail. > > This is the case in your setup as tc358762_init() is called in > tc358762_pre_enable(). > > I think that requiring to initialize the DSI host during transfer could > be avoided in this case by moving tc358762_init() from > tc358762_pre_enable() to tc358762_enable(). > > But at the same time according to the docs at [1] this seems to be a > valid case that we need to support in the DSIM driver: > > Whilst it is valid to call host_transfer prior to pre_enable or > after post_disable, the exact state of the lanes is undefined at > this point. The DSI host should initialise the interface, transmit > the data, and then disable the interface again. > > Therefore I would propose to try a fix like in the attachement. If you > could test this, that would be great. > > Thanks > Frieder > > [1] > https://docs.kernel.org/gpu/drm-kms-helpers.html#mipi-dsi-bridge-operation Hi Frieder, The patch does not resolve the issue. I still get the 'xfer timed out' from samsung-dsim but noticing today that this issue doesn't exist in linux-next I've found that its resolved by Marek's patch: commit 8a4b2fc9c91a ("drm/bridge: tc358762: Split register programming from pre-enable to enable") I'm not clear on how that patch is staged in linux-next. If we can get that pulled into 6.5 then it will resolve the breakage. best regards, Tim
