On Fri, 20 May 2022, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > On Fri, May 20, 2022 at 12:46:00PM +0300, Jani Nikula wrote: >> The VBT send packet port selection was never updated for ICL+ where the >> 2nd link is on port B instead of port C as in VLV+ DSI. >> >> First, single link DSI needs to use the configured port instead of >> relying on the VBT sequence block port. Remove the hard-coded port C >> check here and make it generic. For reference, see commit f915084edc5a >> ("drm/i915: Changes related to the sequence port no for") for the >> original VLV specific fix. >> >> Second, the sequence block port number is either 0 or 1, where 1 >> indicates the 2nd link. Remove the hard-coded port C here for 2nd >> link. (This could be a "find second set bit" on DSI ports, but just >> check the two possible options.) >> >> Third, sanity check the result with a warning to avoid a NULL pointer >> dereference. >> >> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5984 >> Cc: stable@xxxxxxxxxxxxxxx # v4.19+ >> Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> >> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> >> --- >> drivers/gpu/drm/i915/display/intel_dsi_vbt.c | 33 +++++++++++++------- >> 1 file changed, 22 insertions(+), 11 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/display/intel_dsi_vbt.c b/drivers/gpu/drm/i915/display/intel_dsi_vbt.c >> index f370e9c4350d..dd24aef925f2 100644 >> --- a/drivers/gpu/drm/i915/display/intel_dsi_vbt.c >> +++ b/drivers/gpu/drm/i915/display/intel_dsi_vbt.c >> @@ -125,9 +125,25 @@ struct i2c_adapter_lookup { >> #define ICL_GPIO_DDPA_CTRLCLK_2 8 >> #define ICL_GPIO_DDPA_CTRLDATA_2 9 >> >> -static enum port intel_dsi_seq_port_to_port(u8 port) >> +static enum port intel_dsi_seq_port_to_port(struct intel_dsi *intel_dsi, >> + u8 seq_port) >> { >> - return port ? PORT_C : PORT_A; >> + /* >> + * If single link DSI is being used on any port, the VBT sequence block >> + * send packet apparently always has 0 for the port. Just use the port >> + * we have configured, and ignore the sequence block port. >> + */ >> + if (hweight8(intel_dsi->ports) == 1) >> + return ffs(intel_dsi->ports) - 1; >> + >> + if (seq_port) { >> + if (intel_dsi->ports & PORT_B) >> + return PORT_B; >> + else if (intel_dsi->ports & PORT_C) >> + return PORT_C; >> + } >> + >> + return PORT_A; > > Hmm. I guess a bit more generic way to express that could be > to just pick the Nth set bit from intel_dsi->ports, where N==seq_port. > Assuming seq_port is just an index. But I guess we're not really > expecting to grow more DSI ports any time soon, so this seems > sufficient for the current situation. > > Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Thanks, pushed to drm-intel-next. BR, Jani. > >> } >> >> static const u8 *mipi_exec_send_packet(struct intel_dsi *intel_dsi, >> @@ -149,15 +165,10 @@ static const u8 *mipi_exec_send_packet(struct intel_dsi *intel_dsi, >> >> seq_port = (flags >> MIPI_PORT_SHIFT) & 3; >> >> - /* For DSI single link on Port A & C, the seq_port value which is >> - * parsed from Sequence Block#53 of VBT has been set to 0 >> - * Now, read/write of packets for the DSI single link on Port A and >> - * Port C will based on the DVO port from VBT block 2. >> - */ >> - if (intel_dsi->ports == (1 << PORT_C)) >> - port = PORT_C; >> - else >> - port = intel_dsi_seq_port_to_port(seq_port); >> + port = intel_dsi_seq_port_to_port(intel_dsi, seq_port); >> + >> + if (drm_WARN_ON(&dev_priv->drm, !intel_dsi->dsi_hosts[port])) >> + goto out; >> >> dsi_device = intel_dsi->dsi_hosts[port]->device; >> if (!dsi_device) { >> -- >> 2.30.2 -- Jani Nikula, Intel Open Source Graphics Center