On 2019-12-06 5:56 p.m., David (Dingchen) Zhang wrote:

[why] We need to minimally initialize the remote aux channel, e.g. the crc work struct of remote aux to dump the sink's DPRX CRCs in MST setup.

[how] Add helper that only initializes the crc work struct of the remote aux, hooke crc work queue to 'drm_dp_aux_crc_work'. Then call this helper in DP MST port initialization. This, plus David Francis' patch [1], fix the issue of MST remote aux DPCD CRCs read.

[1] https://patchwork.kernel.org/patch/11217941/

Cc: Leo Li sunpeng.li@amd.com Cc: Harry Wentland Harry.Wentland@amd.com Signed-off-by: David (Dingchen) Zhang dingchen.zhang@amd.com

Patch is Reviewed-by: Harry Wentland harry.wentland@amd.com

Harry

---

drivers/gpu/drm/drm_dp_helper.c | 13 +++++++++++++ drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++ include/drm/drm_dp_helper.h | 1 + 3 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 2c7870aef469..cc4845d0fcb8 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -968,6 +968,19 @@ static void drm_dp_aux_crc_work(struct work_struct *work) } }

+/**

• • drm_dp_remote_aux_init() - minimally initialise a remote aux channel
• • @aux: DisplayPort AUX channel
• • Used for remote aux channel in general. Merely initialize the crc work
• • struct.
• */

+void drm_dp_remote_aux_init(struct drm_dp_aux *aux) +{

• INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work);

+} +EXPORT_SYMBOL(drm_dp_remote_aux_init);

/**

• drm_dp_aux_init() - minimally initialise an aux channel
• @aux: DisplayPort AUX channel

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 87fc44895d83..edafa182264a 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1945,6 +1945,9 @@ drm_dp_mst_handle_link_address_port(struct drm_dp_mst_branch *mstb, port->aux.dev = dev->dev; port->aux.is_remote = true;

• /* initialize the MST downstream port's AUX crc work queue */
  

• drm_dp_remote_aux_init(&port->aux);
  

• /*
  • Make sure the memory allocation for our parent branch stays
  • around until our own memory allocation is released

diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 8f8f3632e697..b2e6923d5929 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -1465,6 +1465,7 @@ int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]); void drm_dp_downstream_debug(struct seq_file *m, const u8 dpcd[DP_RECEIVER_CAP_SIZE], const u8 port_cap[4], struct drm_dp_aux *aux);

+void drm_dp_remote_aux_init(struct drm_dp_aux *aux); void drm_dp_aux_init(struct drm_dp_aux *aux); int drm_dp_aux_register(struct drm_dp_aux *aux); void drm_dp_aux_unregister(struct drm_dp_aux *aux);