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drm/dp_mst: Add helper to get port number at specific LCT from RAD

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Add a helper drm_dp_mst_get_ufp_num_at_lct_from_rad() to extract the up
facing port number at specific link count from the RAD. Use the added
helper in drm_dp_mst_rad_to_str() & drm_dp_get_mst_branch_device() to
unify the implementation.

V2:
- Adjust the code format (Lyude)

V3:
- Adjust parameter "rad" of drm_dp_mst_get_ufp_num_at_lct_from_rad() to
be constant (Kernel test robot)

Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Lyude Paul <lyude@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
[fixed commit message typo]
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250113091100.3314533-3-Wayne.Lin@amd.com
This commit is contained in:
Wayne Lin
2025-01-13 17:11:00 +08:00
committed by Lyude Paul
parent 6bbce873a9
commit 580aa2782c
1 changed files with 20 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/gpu/drm/display/drm_dp_mst_topology.c
+20 -9
View File
@@ -171,18 +171,30 @@ static const char *drm_dp_mst_sideband_tx_state_str(int state)
return sideband_reason_str[state];
}
static inline u8
drm_dp_mst_get_ufp_num_at_lct_from_rad(u8 lct, const u8 *rad)
{
int idx = (lct / 2) - 1;
int shift = (lct % 2) ? 0 : 4;
u8 ufp_num;
/* mst_primary, it's rad is unset*/
if (lct == 1)
return 0;
ufp_num = (rad[idx] >> shift) & 0xf;
return ufp_num;
}
static int
drm_dp_mst_rad_to_str(const u8 rad[8], u8 lct, char *out, size_t len)
{
int i;
u8 unpacked_rad[16] = {};
for (i = 1; i < lct; i++) {
if (i % 2)
unpacked_rad[i] = rad[(i - 1) / 2] >> 4;
else
unpacked_rad[i] = rad[(i - 1) / 2] & 0xF;
}
for (i = 0; i < lct; i++)
unpacked_rad[i] = drm_dp_mst_get_ufp_num_at_lct_from_rad(i + 1, rad);
/* TODO: Eventually add something to printk so we can format the rad
* like this: 1.2.3
@@ -2544,9 +2556,8 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
if (!mstb)
goto out;
for (i = 0; i < lct - 1; i++) {
int shift = (i % 2) ? 0 : 4;
int port_num = (rad[i / 2] >> shift) & 0xf;
for (i = 1; i < lct; i++) {
int port_num = drm_dp_mst_get_ufp_num_at_lct_from_rad(i + 1, rad);
list_for_each_entry(port, &mstb->ports, next) {
if (port->port_num == port_num) {