| Message ID | 20220517082817.1591526-1-tzungbi@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | platform/chrome: cros_ec_proto: update cros_ec_check_result() comment | expand |
On Tue, May 17, 2022 at 04:28:17PM +0800, Tzung-Bi Shih wrote: > At first glance, cros_ec_check_result() is quite like cros_ec_map_error(). > They check for `ec_msg->result` and return corresponding errors. However, > as calling from `pkt_xfer` and `cmd_xfer`, cros_ec_check_result() should > not report furthermore errors. -EAGAIN is the only exception. > > See [1][2][3] for some known userland programs' code. The return code > from ioctl only denotes the EC communication status. Userland programs > would further analyze the `result` in struct cros_ec_command* for > follow-up actions (e.g. [4]). > > To clarify, update the function comment. Pardon me if it is confusing. The patch now merged into a series in order to make more sense. Let's ignore the patch and move discussion to [5] if any. [5]: https://patchwork.kernel.org/project/chrome-platform/patch/20220518091814.2028579-4-tzungbi@kernel.org/
diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c index ff767dccdf0f..48b28745bb84 100644 --- a/drivers/platform/chrome/cros_ec_proto.c +++ b/drivers/platform/chrome/cros_ec_proto.c @@ -199,9 +199,12 @@ EXPORT_SYMBOL(cros_ec_prepare_tx); * @msg: Message to check. * * This is used by ChromeOS EC drivers to check the ec_msg->result for - * errors and to warn about them. + * EC_RES_IN_PROGRESS and to warn about them. * - * Return: 0 on success or negative error code. + * The function should not check for furthermore error codes. Otherwise, + * it would break the ABI. + * + * Return: -EAGAIN if ec_msg->result == EC_RES_IN_PROGRESS. Otherwise, 0. */ int cros_ec_check_result(struct cros_ec_device *ec_dev, struct cros_ec_command *msg)
At first glance, cros_ec_check_result() is quite like cros_ec_map_error(). They check for `ec_msg->result` and return corresponding errors. However, as calling from `pkt_xfer` and `cmd_xfer`, cros_ec_check_result() should not report furthermore errors. -EAGAIN is the only exception. See [1][2][3] for some known userland programs' code. The return code from ioctl only denotes the EC communication status. Userland programs would further analyze the `result` in struct cros_ec_command* for follow-up actions (e.g. [4]). To clarify, update the function comment. [1]: https://crrev.com/54400e93a75ef440a83d6eaac2cec066daf99cf0/util/comm-dev.c#154 [2]: https://crrev.com/fe32670a89bf59e1aff84bba9dd3295657b85e9b/cros_ec_dev.c#296 [3]: https://crrev.com/5952a561abaeed1491294a33883d6fd2c2c4089f/drivers/google/cros_ec_dev.c#120 [4]: https://crrev.com/54400e93a75ef440a83d6eaac2cec066daf99cf0/util/comm-dev.c#164 Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org> --- Also see commit 57b888ca2541 ("platform/chrome: Re-introduce cros_ec_cmd_xfer and use it for ioctls") in for-next branch for some other details. The patch bases on the latest for-kernelci branch. (https://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux.git/commit/?h=for-kernelci&id=0534c15c9291a0d571d813fa7c54358736d9ef4c) drivers/platform/chrome/cros_ec_proto.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) base-commit: 0534c15c9291a0d571d813fa7c54358736d9ef4c