Re: [PATCH] i2c: i2c-mux-pca954x: only reset last channel on error

[Peter Rosin]

On 2016-12-16 22:08, Vivien Didelot wrote:
> The current code is selecting the mux channel before each operation and
> does not benefit from the cached value (data->last_chan).
> 
> That is because pca954x_select_chan() considers any non-zero values from
> pca954x_reg_write() as an error. But this function (via __i2c_transfer)
> returns either a negative error code or the positive number of messages
> executed.
> 
> Only check "ret" against negative values to restore the caching.
> 
> Fixes: 463e8f845cbf ("i2c: mux: pca954x: retry updating the mux selection on failure")
> Signed-off-by: Vivien Didelot <vivien.didelot@xxxxxxxxxxxxxxxxxxxx>

Hi Vivien,

Thanks for the report, and sorry for breaking things. However, your
patch got beaten by an hour by Russel King who sent approximately
the same patch. I had already responded to his message when I saw
yours, so I did not Cc you.

Cheers,
peda