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Shashank
On 7/12/2017 10:45 PM, Ville Syrjälä wrote:
On Mon, Jul 10, 2017 at 04:48:44PM +0530, Shashank Sharma wrote:
This patch adds a helper function in DP dual mode layer to
read the vendor's IEEE OUI signature from a Dual mode adapter.
This will be used to differentiate between different LSPCON
vendors, to address their custom programming requirements.
Can't we just read it from DPCD instead?
You are right, as we have DPCD cached, we can do it from DPCD too, and
in fact that was my first implementation.
But then I thought what if some driver doesn't cache DPCD, so thought it
would be good to have a helper function
to check this out.
If you think DPCD would be a better idea, I need not to touch DRM layer
at all, and this will be only I915 implementation.
- Shashank
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Imre Deak <imre.deak@xxxxxxxxx>
Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
---
drivers/gpu/drm/drm_dp_dual_mode_helper.c | 24 ++++++++++++++++++++++++
include/drm/drm_dp_dual_mode_helper.h | 4 +++-
2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
index 80e62f6..0b890dc 100644
--- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
+++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
@@ -396,6 +396,30 @@ const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type)
EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
/**
+ * drm_lspcon_get_vendor_oui: match vendor OUI signature
+ * @adapter: i2c adapter under action
+ * @vendor_id = 3 bytes of vendor OUI signature, LSB=lower byte
+ *
+ * Returns:
+ * Vendor OUI id if got one, 0 if not
+ */
+uint32_t drm_lspcon_get_vendor_oui(struct i2c_adapter *adapter)
+{
+ uint8_t sign[3] = {0, };
+ uint32_t oui = 0;
+
+ if (drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_LSPCON_OUI_OFFSET,
+ sign, 3)) {
+ DRM_ERROR("Can't identify vendor sign\n");
+ return 0;
+ }
+
+ oui = (sign[0] << 16) | (sign[1] << 8) | sign[2];
+ return oui;
+}
+EXPORT_SYMBOL(drm_lspcon_get_vendor_oui);
+
+/**
* drm_lspcon_get_mode: Get LSPCON's current mode of operation by
* reading offset (0x80, 0x41)
* @adapter: I2C-over-aux adapter
diff --git a/include/drm/drm_dp_dual_mode_helper.h b/include/drm/drm_dp_dual_mode_helper.h
index 4c42db8..f81b526 100644
--- a/include/drm/drm_dp_dual_mode_helper.h
+++ b/include/drm/drm_dp_dual_mode_helper.h
@@ -60,7 +60,8 @@
/* LSPCON specific registers, defined by MCA */
#define DP_DUAL_MODE_LSPCON_MODE_CHANGE 0x40
#define DP_DUAL_MODE_LSPCON_CURRENT_MODE 0x41
-#define DP_DUAL_MODE_LSPCON_MODE_PCON 0x1
+#define DP_DUAL_MODE_LSPCON_MODE_PCON 0x1
+#define DP_DUAL_MODE_LSPCON_OUI_OFFSET 0x11
struct i2c_adapter;
@@ -116,4 +117,5 @@ int drm_lspcon_get_mode(struct i2c_adapter *adapter,
enum drm_lspcon_mode *current_mode);
int drm_lspcon_set_mode(struct i2c_adapter *adapter,
enum drm_lspcon_mode reqd_mode);
+uint32_t drm_lspcon_get_vendor_oui(struct i2c_adapter *adapter);
#endif
--
2.7.4
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