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    SubjectRe: [PATCH] platform/chrome: cros_ec_proto: Fix check_features ret val
    Hi Enric,

    Thanks for reviewing the patch.

    On Tue, Sep 21, 2021 at 01:42:04PM +0200, Enric Balletbo i Serra wrote:
    > Hi Prashant,
    >
    > Thank you for the patch. Just one comment below ...
    >
    > On 16/9/21 3:46, Prashant Malani wrote:
    > > The kerneldoc for cros_ec_check_features() states that it returns 1 or 0
    > > depedending on whether a feature is supported or not, but it instead
    > > returns a negative error number in one case, and a non-1 bitmask in
    > > other cases.
    > >
    > > Since all call-sites only check for a 1 or 0 return value, update
    > > the function to return boolean values.
    > >
    > > Signed-off-by: Prashant Malani <pmalani@chromium.org>
    > > ---
    > > drivers/platform/chrome/cros_ec_proto.c | 12 +++++++-----
    > > include/linux/platform_data/cros_ec_proto.h | 2 +-
    > > 2 files changed, 8 insertions(+), 6 deletions(-)
    > >
    > > diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
    > > index a7404d69b2d3..a34cf58c5ef7 100644
    > > --- a/drivers/platform/chrome/cros_ec_proto.c
    > > +++ b/drivers/platform/chrome/cros_ec_proto.c
    > > @@ -808,9 +808,9 @@ EXPORT_SYMBOL(cros_ec_get_host_event);
    > > *
    > > * Call this function to test whether the ChromeOS EC supports a feature.
    > > *
    > > - * Return: 1 if supported, 0 if not
    > > + * Return: true if supported, false if not (or if an error was encountered).
    > > */
    > > -int cros_ec_check_features(struct cros_ec_dev *ec, int feature)
    > > +bool cros_ec_check_features(struct cros_ec_dev *ec, int feature)
    > > {
    > > struct cros_ec_command *msg;
    > > int ret;
    > > @@ -818,8 +818,10 @@ int cros_ec_check_features(struct cros_ec_dev *ec, int feature)
    > > if (ec->features[0] == -1U && ec->features[1] == -1U) {
    > > /* features bitmap not read yet */
    > > msg = kzalloc(sizeof(*msg) + sizeof(ec->features), GFP_KERNEL);
    > > - if (!msg)
    > > - return -ENOMEM;
    > > + if (!msg) {
    > > + dev_err(ec->dev, "failed to allocate memory to get EC features\n");
    >
    > In case of failure you will be noticed by the allocator, prints after
    > [k|v][m|z|c]alloc() functions are not needed, so I think you can just return
    > false here.
    > >

    Makes sense; I can make the change, but I had one question:

    If we solely return false, how will we tell from the logs that the
    allocation error message was associated with this driver? Only returning
    false means the driver probe (e.g cros-ec-typec) will continue (just assuming a certain feature
    is not present). Wouldn't having this error message make this clear?

    Best regards,

    -Prashant

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