On Tue May 23, 2023 at 5:45 AM EEST, wrote: > From: Peijie Shao <shaopeijie@xxxxxxxx> > > The failure paths in tpm_tis_spi_transfer() do not deactivate > chip select. Send an empty message (cs_select == 0) to overcome > this. > > The patch is tested by two ways. > One way needs to touch hardware: > 1. force pull MISO pin down to GND, it emulates a forever > 'WAIT' timing. > 2. probe cs pin by an oscilloscope. > 3. load tpm_tis_spi.ko. > After loading, dmesg prints: > "probe of spi0.0 failed with error -110" > and oscilloscope shows cs pin goes high(deactivated) after > the failure. Before the patch, cs pin keeps low. > > Second way is by writing a fake spi controller. > 1. implement .transfer_one method, fill all rx buf with 0. > 2. implement .set_cs method, print the state of cs pin. > we can see cs goes high after the failure. > > Signed-off-by: Peijie Shao <shaopeijie@xxxxxxxx> Looks good to me + great explanation, thank you. Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> BR, Jarkko
