[PATCH v5 06/15] drm/bridge: tc358767: Simplify AUX data read

[Andrey Smirnov]

Simplify AUX data read by removing index arithmetic and shifting with
a helper function that does two things:

    1. Fetch data from up to 4 32-bit registers from the chip
    2. Copy read data into user provided array.

Signed-off-by: Andrey Smirnov <andrew.smir...@gmail.com>
Reviewed-by: Andrzej Hajda <a.ha...@samsung.com>
Cc: Andrzej Hajda <a.ha...@samsung.com>
Cc: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
Cc: Tomi Valkeinen <tomi.valkei...@ti.com>
Cc: Andrey Gusakov <andrey.gusa...@cogentembedded.com>
Cc: Philipp Zabel <p.za...@pengutronix.de>
Cc: Cory Tusar <cory.tu...@zii.aero>
Cc: Chris Healy <cphe...@gmail.com>
Cc: Lucas Stach <l.st...@pengutronix.de>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-ker...@vger.kernel.org
---
 drivers/gpu/drm/bridge/tc358767.c | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/bridge/tc358767.c 
b/drivers/gpu/drm/bridge/tc358767.c
index 7b15caec2ce5..7152b44db8a3 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -321,6 +321,20 @@ static int tc_aux_get_status(struct tc_data *tc, u8 *reply)
        return 0;
 }
 
+static int tc_aux_read_data(struct tc_data *tc, void *data, size_t size)
+{
+       u32 auxrdata[DP_AUX_MAX_PAYLOAD_BYTES / sizeof(u32)];
+       int ret, count = ALIGN(size, sizeof(u32));
+
+       ret = regmap_raw_read(tc->regmap, DP0_AUXRDATA(0), auxrdata, count);
+       if (ret)
+               return ret;
+
+       memcpy(data, auxrdata, size);
+
+       return size;
+}
+
 static ssize_t tc_aux_transfer(struct drm_dp_aux *aux,
                               struct drm_dp_aux_msg *msg)
 {
@@ -379,19 +393,10 @@ static ssize_t tc_aux_transfer(struct drm_dp_aux *aux,
        if (ret)
                return ret;
 
-       if (request == DP_AUX_I2C_READ || request == DP_AUX_NATIVE_READ) {
-               /* Read data */
-               while (i < size) {
-                       if ((i % 4) == 0) {
-                               ret = regmap_read(tc->regmap,
-                                                 DP0_AUXRDATA(i >> 2), &tmp);
-                               if (ret)
-                                       return ret;
-                       }
-                       buf[i] = tmp & 0xff;
-                       tmp = tmp >> 8;
-                       i++;
-               }
+       switch (request) {
+       case DP_AUX_NATIVE_READ:
+       case DP_AUX_I2C_READ:
+               return tc_aux_read_data(tc, msg->buffer, size);
        }
 
        return size;
-- 
2.21.0