2017-06-20 19:31 GMT+02:00 Eric Anholt <eric@xxxxxxxxxx>: > Archit Taneja <architt@xxxxxxxxxxxxxx> writes: > >> On 06/16/2017 08:13 PM, Eric Anholt wrote: >>> Archit Taneja <architt@xxxxxxxxxxxxxx> writes: >>> >>>> On 06/16/2017 02:11 AM, Eric Anholt wrote: >>>>> If the panel-bridge is being set up after the drm_mode_config_reset(), >>>>> then the connector's state would never get initialized, and we'd >>>>> dereference the NULL in the hotplug path. We also need to register >>>>> the connector, so that userspace can get at it. >>>>> >>>> >>>> Shouldn't the KMS driver make sure the panel-bridge is set up before >>>> drm_mode_config_reset? Is it the case when we're inserting the >>>> panel-bridge driver as a module? >>>> >>>> >>>> All the connectors that have been added are registered automatically >>>> when drm_dev_register() is called by the KMS driver. Registering a >>>> connector in the middle of setting up our driver is prone to race >>>> conditions if the userspace decides to use them immediately. >>> >>> Yeah, this is fixing initializing panel_bridge at DSI host_attach time, >>> which in the case of a panel module that creates the DSI device >>> (adv7533-style, like you said I should use as a reference) will be after >>> drm_mode_config_reset() and drm_dev_register(). >> >> Okay. In the case of the msm kms driver, we defer probe until the >> adv7533 module is inserted, only then we proceed to drm_mode_config_reset() >> and drm_dev_register(). I assumed this was the general practice followed by >> most kms drivers. I.,e the kms driver defers probe until all connector >> related modules are inserted, and only then proceed to create a drm device. > > The problem, though, is the panel driver needs the MIPI DSI host to > exist to call mipi_dsi_device_register_full() during the probe process. > The adv7533 driver gets around this by registering the DSI device in the > bridge attach step, but drm_panel doesn't have an attach step. > > Another alternative is my original version of the panel driver that was > a mipi_dsi_device driver that registered the panel during the DSI device > probe. That's why vc4's panel lookup is during the MIPI DSI attach > phase, currently. + Philippe in copy because we have the same probing issue when adding panel-bridge with the dsi bridge > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
