drm/dp: Add drm_dp_psr_setup_time()

Add a small helper to parse the PSR setup time from the DPCD PSR
capabilities and return the value in microseconds.

v2: Don't waste so many bytes on the psr_setup_time_us[] table

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 34 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 8f11b8741e42..eae5ef963cb7 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -860,3 +860,35 @@ void drm_dp_aux_unregister(struct drm_dp_aux *aux)
         i2c_del_adapter(&aux->ddc);
 }
 EXPORT_SYMBOL(drm_dp_aux_unregister);
+
+#define PSR_SETUP_TIME(x) [DP_PSR_SETUP_TIME_ ## x >> DP_PSR_SETUP_TIME_SHIFT] = (x)
+
+/**
+ * drm_dp_psr_setup_time() - PSR setup in time usec
+ * @psr_cap: PSR capabilities from DPCD
+ *
+ * Returns:
+ * PSR setup time for the panel in microseconds,  negative
+ * error code on failure.
+ */
+int drm_dp_psr_setup_time(const u8 psr_cap[EDP_PSR_RECEIVER_CAP_SIZE])
+{
+        static const u16 psr_setup_time_us[] = {
+                PSR_SETUP_TIME(330),
+                PSR_SETUP_TIME(275),
+                PSR_SETUP_TIME(165),
+                PSR_SETUP_TIME(110),
+                PSR_SETUP_TIME(55),
+                PSR_SETUP_TIME(0),
+        };
+        int i;
+
+        i = (psr_cap[1] & DP_PSR_SETUP_TIME_MASK) >> DP_PSR_SETUP_TIME_SHIFT;
+        if (i >= ARRAY_SIZE(psr_setup_time_us))
+                return -EINVAL;
+
+        return psr_setup_time_us[i];
+}
+EXPORT_SYMBOL(drm_dp_psr_setup_time);
+
+#undef PSR_SETUP_TIME
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 72dee1213268..63b8bd502444 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -657,6 +657,8 @@ struct edp_vsc_psr {
 #define EDP_VSC_PSR_UPDATE_RFB          (1<<1)
 #define EDP_VSC_PSR_CRC_VALUES_VALID    (1<<2)
 
+int drm_dp_psr_setup_time(const u8 psr_cap[EDP_PSR_RECEIVER_CAP_SIZE]);
+
 static inline int
 drm_dp_max_link_rate(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 {