drm/radeon/atom: fix bus probes when hw_i2c is set (v2)

When probing the bus, we need to set the byte count
to 0 rather than 1.

v2: Don't count the first byte.

bug:
https://bugzilla.kernel.org/show_bug.cgi?id=66241

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/radeon/atombios_i2c.c b/drivers/gpu/drm/radeon/atombios_i2c.c
index 0652ee0..f685035 100644 (file)
--- a/drivers/gpu/drm/radeon/atombios_i2c.c
+++ b/drivers/gpu/drm/radeon/atombios_i2c.c
@@ -44,7 +44,7 @@ static int radeon_process_i2c_ch(struct radeon_i2c_chan *chan,
        PROCESS_I2C_CHANNEL_TRANSACTION_PS_ALLOCATION args;
        int index = GetIndexIntoMasterTable(COMMAND, ProcessI2cChannelTransaction);
        unsigned char *base;
-       u16 out;
+       u16 out = cpu_to_le16(0);
 
        memset(&args, 0, sizeof(args));
 
@@ -55,11 +55,14 @@ static int radeon_process_i2c_ch(struct radeon_i2c_chan *chan,
                        DRM_ERROR("hw i2c: tried to write too many bytes (%d vs 3)\n", num);
                        return -EINVAL;
                }
-               args.ucRegIndex = buf[0];
-               if (num > 1) {
+               if (buf == NULL)
+                       args.ucRegIndex = 0;
+               else
+                       args.ucRegIndex = buf[0];
+               if (num)
                        num--;
+               if (num)
                        memcpy(&out, &buf[1], num);
-               }
                args.lpI2CDataOut = cpu_to_le16(out);
        } else {
                if (num > ATOM_MAX_HW_I2C_READ) {
@@ -96,14 +99,14 @@ int radeon_atom_hw_i2c_xfer(struct i2c_adapter *i2c_adap,
        struct radeon_i2c_chan *i2c = i2c_get_adapdata(i2c_adap);
        struct i2c_msg *p;
        int i, remaining, current_count, buffer_offset, max_bytes, ret;
-       u8 buf = 0, flags;
+       u8 flags;
 
        /* check for bus probe */
        p = &msgs[0];
        if ((num == 1) && (p->len == 0)) {
                ret = radeon_process_i2c_ch(i2c,
                                            p->addr, HW_I2C_WRITE,
-                                           &buf, 1);
+                                           NULL, 0);
                if (ret)
                        return ret;
                else