Re: [PATCH net-next 2/2] net: dsa: mv88e6xxx: Improve indirect addressing performance

From: Andrew Lunn
Date: Wed Jan 26 2022 - 18:53:36 EST


On Thu, Jan 27, 2022 at 12:12:39AM +0100, Tobias Waldekranz wrote:
> Before this change, both the read and write callback would start out
> by asserting that the chip's busy flag was cleared. However, both
> callbacks also made sure to wait for the clearing of the busy bit
> before returning - making the initial check superfluous. The only
> time that would ever have an effect was if the busy bit was initially
> set for some reason.
>
> With that in mind, make sure to perform an initial check of the busy
> bit, after which both read and write can rely the previous operation
> to have waited for the bit to clear.
>
> This cuts the number of operations on the underlying MDIO bus by 25%
>
> Signed-off-by: Tobias Waldekranz <tobias@xxxxxxxxxxxxxx>

Reviewed-by: Andrew Lunn <andrew@xxxxxxx>

Andrew