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 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html