Messages in this thread | | | Subject | Re: [PATCH 1/7] drm/bridge: Support hotplugging panel-bridge. | From | Archit Taneja <> | Date | Tue, 20 Jun 2017 09:18:00 +0530 |
| |
On 06/16/2017 08:13 PM, Eric Anholt wrote: > Archit Taneja <architt@codeaurora.org> 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.
Feedback from others on this would be appreciated, though.
Thanks, Archit
-- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
| |