Hi Zain, On Mon, Feb 13, 2017 at 6:27 PM, zain wang <wzz@xxxxxxxxxxxxxx> wrote: > > The analogix_dp_transfer() will return -EBUSY if num_transferred is zero. > But sometimes we will send a bare address packet to start the transaction, > like drm_dp_i2c_xfer() show: > ...... > /* Send a bare address packet to start the transaction. > * Zero sized messages specify an address only (bare > * address) transaction. > */ > msg.buffer = NULL; > msg.size = 0; > err = drm_dp_i2c_do_msg(aux, &msg); > ...... > > In this case, the msg->size is zero, so the num_transferred will be zero too. > We can't return -EBUSY here, let's we return num_transferred if num_transferred > equals msg->size. > Please see my question inline. > Signed-off-by: zain wang <wzz@xxxxxxxxxxxxxx> > --- > drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c > index 303083a..5384aca 100644 > --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c > +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c > @@ -1162,5 +1162,5 @@ ssize_t analogix_dp_transfer(struct analogix_dp_device *dp, > (msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_NATIVE_READ) > msg->reply = DP_AUX_NATIVE_REPLY_ACK; > > - return num_transferred > 0 ? num_transferred : -EBUSY; > + return (num_transferred == msg->size) ? num_transferred : -EBUSY; I might be missing something but, looking at the code, I don't see any possibility of num_transferred ever being different than msg->size. To be honest, it doesn't seem to even make any sense keeping the local variable there, because msg->size can be simply always returned, as errors are handled by jumping to aux_error label. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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