On Mon, Jul 24, 2023 at 8:16 AM Frieder Schrempf <frieder@xxxxxxx> wrote: > > From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx> > > In case the downstream bridge or panel uses DSI transfers before the > DSI host was actually initialized through samsung_dsim_atomic_enable() > which clears the stop state (LP11) mode, all transfers will fail. > > This happens with downstream bridges that are controlled by DSI > commands such as the tc358762. > > As documented in [1] DSI hosts are expected to allow transfers > outside the normal bridge enable/disable flow. > > To fix this make sure that stop state is cleared in > samsung_dsim_host_transfer() which restores the previous > behavior. > > We also factor out the common code to enable/disable stop state > to samsung_dsim_set_stop_state(). > > [1] https://docs.kernel.org/gpu/drm-kms-helpers.html#mipi-dsi-bridge-operation > > Fixes: 0c14d3130654 ("drm: bridge: samsung-dsim: Fix i.MX8M enable flow to meet spec") > Reported-by: Tim Harvey <tharvey@xxxxxxxxxxxxx> > Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx> > --- > Changes for v2: > * Fix reversed stop state enable/disable in samsung_dsim_set_stop_state() > > Hi Tim, could you please give this patch a try and report back if > it fixes your problem? Thanks! > --- > drivers/gpu/drm/bridge/samsung-dsim.c | 27 +++++++++++++++++---------- > 1 file changed, 17 insertions(+), 10 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c > index 043b8109e64a..73ec60757dbc 100644 > --- a/drivers/gpu/drm/bridge/samsung-dsim.c > +++ b/drivers/gpu/drm/bridge/samsung-dsim.c > @@ -1386,6 +1386,18 @@ static void samsung_dsim_disable_irq(struct samsung_dsim *dsi) > disable_irq(dsi->irq); > } > > +static void samsung_dsim_set_stop_state(struct samsung_dsim *dsi, bool enable) > +{ > + u32 reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG); > + > + if (enable) > + reg |= DSIM_FORCE_STOP_STATE; > + else > + reg &= ~DSIM_FORCE_STOP_STATE; > + > + samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg); > +} > + > static int samsung_dsim_init(struct samsung_dsim *dsi) > { > const struct samsung_dsim_driver_data *driver_data = dsi->driver_data; > @@ -1445,15 +1457,12 @@ 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; > > 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); > + samsung_dsim_set_stop_state(dsi, false); > } > > dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE; > @@ -1463,16 +1472,12 @@ 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); > - } > + if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) > + samsung_dsim_set_stop_state(dsi, true); > > dsi->state &= ~DSIM_STATE_VIDOUT_AVAILABLE; > } > @@ -1775,6 +1780,8 @@ static ssize_t samsung_dsim_host_transfer(struct mipi_dsi_host *host, > if (ret) > return ret; > > + samsung_dsim_set_stop_state(dsi, false); > + > ret = mipi_dsi_create_packet(&xfer.packet, msg); > if (ret < 0) > return ret; > -- > 2.41.0 > Frieder, Sorry for the delay. Yes this resolves the regression I ran into. I tested it on top of v6.5-rc6 on a gw72xx-0x with a DFROBOT DRF0678 7in 800x480 (Raspberry Pi) display which has the Toshiba TC358762 compatible DSI to DBI bridge. Let's please get this into v6.5 as soon as possible. Best regards, Tim
