drm/radeon: atombios hw i2c fixes

These fixes make writes work properly.  Previously
only reads worked.  Note that this feature is off
by default.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/radeon/atombios_i2c.c b/drivers/gpu/drm/radeon/atombios_i2c.c
index 2ca389d..deaf98c 100644 (file)
--- a/drivers/gpu/drm/radeon/atombios_i2c.c
+++ b/drivers/gpu/drm/radeon/atombios_i2c.c
@@ -32,7 +32,7 @@ extern void radeon_atom_copy_swap(u8 *dst, u8 *src, u8 num_bytes, bool to_le);
 #define TARGET_HW_I2C_CLOCK 50
 
 /* these are a limitation of ProcessI2cChannelTransaction not the hw */
-#define ATOM_MAX_HW_I2C_WRITE 2
+#define ATOM_MAX_HW_I2C_WRITE 3
 #define ATOM_MAX_HW_I2C_READ  255
 
 static int radeon_process_i2c_ch(struct radeon_i2c_chan *chan,
@@ -52,20 +52,24 @@ static int radeon_process_i2c_ch(struct radeon_i2c_chan *chan,
 
        if (flags & HW_I2C_WRITE) {
                if (num > ATOM_MAX_HW_I2C_WRITE) {
-                       DRM_ERROR("hw i2c: tried to write too many bytes (%d vs 2)\n", num);
+                       DRM_ERROR("hw i2c: tried to write too many bytes (%d vs 3)\n", num);
                        return -EINVAL;
                }
-               memcpy(&out, buf, num);
+               args.ucRegIndex = buf[0];
+               if (num > 1)
+                       memcpy(&out, &buf[1], num - 1);
                args.lpI2CDataOut = cpu_to_le16(out);
        } else {
                if (num > ATOM_MAX_HW_I2C_READ) {
                        DRM_ERROR("hw i2c: tried to read too many bytes (%d vs 255)\n", num);
                        return -EINVAL;
                }
+               args.ucRegIndex = 0;
+               args.lpI2CDataOut = 0;
        }
 
+       args.ucFlag = flags;
        args.ucI2CSpeed = TARGET_HW_I2C_CLOCK;
-       args.ucRegIndex = 0;
        args.ucTransBytes = num;
        args.ucSlaveAddr = slave_addr << 1;
        args.ucLineNumber = chan->rec.i2c_id;