Re: question about i2c_transfer() function (regarding mdio-i2c on RollBall SFPs)

On Thu, 7 Jan 2021 22:02:48 +0100
Wolfram Sang [off-list ref] wrote:

quoted

My question is whether this is allowed, whether the msgs array passed
to the i2c_transfer() function can have multiple msgs pointing to the
same buffer (the one into which the original page is first stored
with first i2c_msg and then restored from it in the last i2c_msg).  

Sending the messages is serialized, so the buffers won't interfere. At
first glance, I think it would work this way. But it's late evening
here, so I will have another look again tomorrow.

I thought as much, but maybe there is some driver which can offload
whole i2c_transfer to HW, and has to pass the addresses of the buffers
to the HW, and the HW can have problems if the buffers overlap
somewhere...

Marek