Re: [PATCH v3 3/5] platform/chrome: cros_ec_proto: Introduce cros_ec_cmd_versions()

[Tzung-Bi Shih <tzungbi@kernel.org>]

On Tue, Jun 11, 2024 at 09:23:24AM +0200, Thomas Weißschuh wrote:
> On 2024-06-11 06:32:38+0000, Tzung-Bi Shih wrote:
> > On Mon, Jun 10, 2024 at 05:51:08PM +0200, Thomas Weißschuh wrote:
> > > If the command is not supported at all the EC returns
> > > -EINVAL/EC_RES_INVALID_PARAMS.
> > > 
> > > This error is translated into an empty version mask as that is easier to
> > > handle for callers and they don't need to know about the error details.
> > 
> > I'm not sure whether the behavior is what we want or not as existing
> > EC_CMD_GET_CMD_VERSIONS usages don't have it.
> 
> At least the caller of cros_ec_get_host_command_version_mask() expects
> it:
> 
> ret = cros_ec_get_host_command_version_mask(..., &ver_mask);
> if (ret < 0 || ver_mask == 0)
> ...
> 
> ver_mask == 0 will never happen as in that case -EINVAL would have been
> returned.
> 
> Others, like cros_ec_cec_get_write_cmd_version(), expect the current
> semantic of ver_mask != 0 but log spurious errors in case of -EINVAL.
> cros_pchg_cmd_ver_check(), works with both semantics, but currently also
> logs a spurious error message.
> 
> To me the new semantic looks more obvious and much easier to handle.
> For each command version a bit is set. no command versions -> no bits.

Ack.