Thanks for the review, Ville.
My comments, inline.

Regards
Shashank
On 5/31/2016 3:22 PM, Ville Syrjälä wrote:
On Tue, May 31, 2016 at 02:55:42PM +0530, Shashank Sharma wrote:
Signed-off-by: Shashank Sharma <[email protected]>
---
  drivers/gpu/drm/drm_dp_dual_mode_helper.c | 85 +++++++++++++++++++++++++++++++
  include/drm/drm_dp_dual_mode_helper.h     | 29 +++++++++++
  2 files changed, 114 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c 
b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
index a7b2a75..11cab25 100644
--- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
+++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
@@ -148,6 +148,12 @@ static bool is_type2_adaptor(uint8_t adaptor_id)
                              DP_DUAL_MODE_REV_TYPE2);
  }

+bool is_lspcon_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN],
+       const uint8_t adaptor_id)
+{
+       return is_hdmi_adaptor(hdmi_id) && (adaptor_id == 0xa8);


I'd probably make this something like

#define DP_DUAL_MODE_RESERVED_LSPCON 0x08

         return adaptor_id == (DP_DUAL_MODE_TYPE_TYPE2 |
                              DP_DUAL_MODE_RESERVED_LSPCON |
                              DP_DUAL_MODE_REV_TYPE2);

Thanks, this is a good suggestion, I will do so.

+}
+
  /**
   * drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
   * @adapter: I2C adapter for the DDC bus
@@ -203,6 +209,8 @@ enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct 
i2c_adapter *adapter)
        ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
                                    &adaptor_id, sizeof(adaptor_id));
        if (ret == 0) {
+               if (is_lspcon_adaptor(hdmi_id, adaptor_id))
+                       return DRM_DP_DUAL_MODE_LSPCON;
                if (is_type2_adaptor(adaptor_id)) {
                        if (is_hdmi_adaptor(hdmi_id))
                                return DRM_DP_DUAL_MODE_TYPE2_HDMI;
@@ -364,3 +372,80 @@ 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_current_mode: Get LSPCON's current mode of operation by
+ * by reading offset (0x80, 0x41)
+ * @i2c_adapter: I2C-over-aux adapter
+ *
+ * Returns:
+ * Enum representing current mode of operation
+ */
+enum drm_lspcon_mode
+drm_lspcon_get_current_mode(struct i2c_adapter *adapter)

To match with drm_dp_dual_mode_get_tmds_output() this may want to
return the error status, and return the actual mode via a function
argument.

sure, can be done.
As for the name drm_dp_dual_mode_get_lspcon_mode() and
drm_dp_dual_mode_set_lspcon_mode() perhaps?
Or drm_lspcon_get_mode()/drm_lspcon_set_mode() perhaps if we want to
keep things shorter?

Yep, initially I made the same names as you suggested, but drm_dp_dual_mode_get_lspcon_mode dint sound good to me :).
drm_lspcon_get/set_mode sounds good.
+{
+       u8 data;
+       int err = 0;

I used 'ret' in the rest of the code. This is a bit inconsistent.
got it.

+
+       /* Read Status: i2c over aux */
+       err = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_LSPCON_CURRENT_MODE,
+                       (void *)&data, sizeof(data));

Pointless cast.

good catch, this is unnecessary.
+       if (err < 0) {

if (ret) is what I've used elsewhere.
got it.

+               DRM_ERROR("LSPCON read(0x80, 0x41) failed\n");

I'm not sure we want and ERROR from a helper. I used DRM_DEBUG_KMS for
the other error paths.

IMHO, This is a failure which needs notice, as it can point out to a HW level problem, or a problem in LSPCON FW, so I will prefer to keep it as error.
+               return DRM_LSPCON_MODE_INVALID;
+       }
+
+       return data & DP_DUAL_MODE_LSPCON_MODE_MASK ?
+               DRM_LSPCON_MODE_PCON : DRM_LSPCON_MODE_LS;
+}
+EXPORT_SYMBOL(drm_lspcon_get_current_mode);
+
+/**
+ * drm_lspcon_change_mode: Change LSPCON's mode of operation by
+ * by writing offset (0x80, 0x40)
+ * @i2c_adapter: I2C-over-aux adapter
+ * @reqd_mode: required mode of operation
+ *
+ * Returns:
+ * 0 on success, -error on failure/timeout
+ */
+int drm_lspcon_change_mode(struct i2c_adapter *adapter,
+       enum drm_lspcon_mode reqd_mode)
+{
+       u8 data;
+       int err;
+       int time_out = 200;
+
+       if (reqd_mode == DRM_LSPCON_MODE_LS)
+               data = ~DP_DUAL_MODE_LSPCON_MODE_MASK;

Is that really correct?

Oops, it was a blunder, but fortunately that register only bothers about bit 0, and that's why it worked, I will fix this.
+       else
+               data = DP_DUAL_MODE_LSPCON_MODE_MASK;
+
+       /* Change mode */
+       err = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_LSPCON_MODE_CHANGE,
+                       &data, sizeof(data));
+       if (err < 0) {
+               DRM_ERROR("LSPCON mode change failed\n");
+               return err;
+       }
+
+       /*
+       * Confirm mode change by reading the status bit.
+       * Sometimes, it takes a while to change the mode,
+       * so wait and retry until time out or done.
+       */

indent fail
OK.

+       while (time_out) {
+               if (reqd_mode != drm_lspcon_get_current_mode(adapter)) {
+                       mdelay(10);

mdelay() is bad.
Do you think I should replace with some of the non-busy wait (like msleep or so ?)

+                       time_out -= 10;
+               } else {
+                       DRM_DEBUG_KMS("LSPCON mode changed to %s\n",
+                       reqd_mode == DRM_LSPCON_MODE_LS ? "LS" : "PCON");
+                       return 0;
+               }
+       }
+
+       DRM_ERROR("LSPCON mode change timed out\n");
+       return -EFAULT;

EFAULT doens't seem like a sensible error value here. ETIMEDOUT I
suppose seems like what we should return.
Sure.

+}
+EXPORT_SYMBOL(drm_lspcon_change_mode);
diff --git a/include/drm/drm_dp_dual_mode_helper.h 
b/include/drm/drm_dp_dual_mode_helper.h
index e8a9dfd..f335df5 100644
--- a/include/drm/drm_dp_dual_mode_helper.h
+++ b/include/drm/drm_dp_dual_mode_helper.h
@@ -24,6 +24,7 @@
  #define DRM_DP_DUAL_MODE_HELPER_H

  #include <linux/types.h>
+#include <drm/drm_edid.h>

  /*
   * Optional for type 1 DVI adaptors
@@ -54,6 +55,9 @@
  #define DP_DUAL_MODE_HDMI_PIN_CTRL 0x21
  #define  DP_DUAL_MODE_CEC_ENABLE 0x01
  #define DP_DUAL_MODE_I2C_SPEED_CTRL 0x22

Maybe leave an empty line here to separate the standard regs from the
vendor specific ones. Hmm. Actually the vendor register space is
0x30-0x3f, whereas 0x40+ is reserved. But anyway empty line would
seem warranted.

Got it.
+#define DP_DUAL_MODE_LSPCON_MODE_CHANGE                0x40
+#define DP_DUAL_MODE_LSPCON_CURRENT_MODE               0x41
+#define DP_DUAL_MODE_LSPCON_MODE_MASK                  0x1

Please indent the bit defnition by one space to make it stand out from
the reg defines a little.

Ok, the first two are registers only, I guess this is for DP_DUAL_MODE_LSPCON_MODE_MASK. I will align it.
  struct i2c_adapter;

@@ -63,6 +67,20 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
                               u8 offset, const void *buffer, size_t size);

  /**
+* enum drm_lspcon_mode
+* @lspcon_mode_invalid: No idea what's going on
+* @lspcon_mode_ls: Level shifter mode of LSPCON
+*      which drives DP++ to HDMI 1.4 conversion.
+* @lspcon_mode_pcon: Protocol converter mode of LSPCON
+*      which drives DP++ to HDMI 2.0 active conversion.
+*/
+enum drm_lspcon_mode {
+       DRM_LSPCON_MODE_INVALID,
+       DRM_LSPCON_MODE_LS,
+       DRM_LSPCON_MODE_PCON,
+};

If we change the _get_mode() thing to return the error status separately
from the mode, we won't need the INVALID value.

Agree.
+
+/**
   * enum drm_dp_dual_mode_type - Type of the DP dual mode adaptor
   * @DRM_DP_DUAL_MODE_NONE: No DP dual mode adaptor
   * @DRM_DP_DUAL_MODE_UNKNOWN: Could be either none or type 1 DVI adaptor
@@ -70,6 +88,7 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
   * @DRM_DP_DUAL_MODE_TYPE1_HDMI: Type 1 HDMI adaptor
   * @DRM_DP_DUAL_MODE_TYPE2_DVI: Type 2 DVI adaptor
   * @DRM_DP_DUAL_MODE_TYPE2_HDMI: Type 2 HDMI adaptor
+ * @DRM_DP_DUAL_MODE_TYPE2_LSPCON: Level shifter /protocol converter
   */
  enum drm_dp_dual_mode_type {
        DRM_DP_DUAL_MODE_NONE,
@@ -78,6 +97,7 @@ enum drm_dp_dual_mode_type {
        DRM_DP_DUAL_MODE_TYPE1_HDMI,
        DRM_DP_DUAL_MODE_TYPE2_DVI,
        DRM_DP_DUAL_MODE_TYPE2_HDMI,
+       DRM_DP_DUAL_MODE_LSPCON,
  };

  enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter 
*adapter);
@@ -89,4 +109,13 @@ int drm_dp_dual_mode_set_tmds_output(enum 
drm_dp_dual_mode_type type,
                                     struct i2c_adapter *adapter, bool enable);
  const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type);

+int drm_dp_dual_mode_ioa_read(struct i2c_adapter *adapter, u8 *buffer,
+               u8 offset, u8 no_of_bytes);
+int drm_dp_dual_mode_ioa_write(struct i2c_adapter *adapter, u8 *buffer,
+               u8 offset, u8 no_of_bytes);
+int drm_dp_dual_mode_get_edid(void *data,
+       u8 *buf, unsigned int block, size_t len);
+enum drm_lspcon_mode drm_lspcon_get_current_mode(struct i2c_adapter *adapter);
+int drm_lspcon_change_mode(struct i2c_adapter *adapter,
+               enum drm_lspcon_mode reqd_mode);
  #endif
--
1.9.1

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