[Added Leo Li here, since they did the auxdev work that introduced these
functions]
Since it seems we'll actually be doing remote DPCD read/writes in DRM drivers
and not just from auxdev, maybe we should combine drm_dp_dpcd_read() with
drm_dp_mst_dpcd_read() and do the same with the _write() variants? Based on
previous discussions with Leo Li I remember that we can't just combine the
dp_aux_dev->transfer() callbacks in struct drm_dp_aux_dev, but I don't see a
reason we can't just teach drm_dp_dpcd_read/write() to work with MST aux so
that we don't need two seperate functions. This should be pretty easy to do,
just:
/* Add a check like this at the start of drm_dp_dpcd_read(): */
ssize_t drm_dp_dpcd_read(...) {
if (aux->is_remote)
return drm_dp_mst_dpcd_read(...);
/* ... */
}
/* And in drm_dp_dpcd_write(): */
ssize_t drm_dp_dpcd_write(...) {
if (aux->is_remote)
return drm_dp_mst_dpcd_write(...);
/* ... */
}
Then just replace the manual calls to drm_dp_mst_dpcd_write() in
drivers/gpu/drm/drm_dp_aux_dev.c with normal
drm_dp_dpcd_read()/drm_dp_dpcd_write() calls. Thoughts?
On Tue, 2019-08-20 at 15:11 -0400, David Francis wrote:
> To use these functions in drm driver directories, they must be
> exported
>
> Signed-off-by: David Francis <david.fran...@amd.com>
> ---
> drivers/gpu/drm/drm_dp_mst_topology.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index b40d975aec76..5d5bd42da17c 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -1512,6 +1512,7 @@ ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux,
> return drm_dp_send_dpcd_read(port->mgr, port,
> offset, size, buffer);
> }
> +EXPORT_SYMBOL(drm_dp_mst_dpcd_read);
>
> /**
> * drm_dp_mst_dpcd_write() - write a series of bytes to the DPCD via
> sideband
> @@ -1535,6 +1536,7 @@ ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux,
> return drm_dp_send_dpcd_write(port->mgr, port,
> offset, size, buffer);
> }
> +EXPORT_SYMBOL(drm_dp_mst_dpcd_write);
>
> static void drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, u8
> *guid)
> {
--
Cheers,
Lyude Paul
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