From patchwork Tue May 17 08:28:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tzung-Bi Shih X-Patchwork-Id: 12852100 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E12427F for ; Tue, 17 May 2022 08:28:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63540C385B8; Tue, 17 May 2022 08:28:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652776116; bh=z0Xym3AE/OPgfmfQslBqghpEiHagGntjg80lX/HSvug=; h=From:To:Cc:Subject:Date:From; b=CIoI/LSeCrZ86ryVm8YaWPWy6y+RC8wZPXQHTvnYcuGGqUoshLt+DHmm2uFKu0+4e A02DiYmSTDAYPPLjpLOsVmw3IFAmTupNAJXZzBtoyRf8EAn4H/TreaZ+IKdHQnpEjf CnZzzQJ8cg434u307h5VpA+B7p4D/iMFuujuKpfRZHtuwdUG5+AENNUfKBT06uSIuf Q953swId4ZeitThTCCQ5/K3QD4ihdB0laZNHOtoXiTyK2+y/I+/ucuqBclUAqdAfP+ Bhb/C5Wa6cbplm0g62h1rFkFl9OboslnnPQFK4Mtium54d5cfs8s6A+0hf+zGp+ZKw RVdnasog857qg== From: Tzung-Bi Shih To: bleung@chromium.org, groeck@chromium.org Cc: chrome-platform@lists.linux.dev, linux-kernel@vger.kernel.org, tzungbi@kernel.org, dianders@chromium.org Subject: [PATCH] platform/chrome: cros_ec_proto: update cros_ec_check_result() comment Date: Tue, 17 May 2022 16:28:17 +0800 Message-Id: <20220517082817.1591526-1-tzungbi@kernel.org> X-Mailer: git-send-email 2.36.0.550.gb090851708-goog Precedence: bulk X-Mailing-List: chrome-platform@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 --- 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 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)