From mboxrd@z Thu Jan 1 00:00:00 1970 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 F1A98306490; Sat, 25 Oct 2025 16:27:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761409638; cv=none; b=c8P2hCZsKMHTe6p1xY6GO5esYiD2ilTRpHdlPdl4+NrftMZTSBTHKDLjS3WR740YKMWhkD3I1m8iHJsAksvFzHcKSjKX+bov2W9f3tGqiKabX0EUpWqyGGQDLIH/4XTHKk4cwpBjySuSB7ivJCHaI40+Hh7k2JH5fL6gBXnnHgQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761409638; c=relaxed/simple; bh=674ScUfL2y2OnNZx6hSiuHRi3Sb7Jh74ZzdnAu96/C0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=J5L5f/4/jjgwyVG6hTdKt8tC6q6O3LxVCd5p/ZrcM0iQdwQDENT07CPc3HNs2efa9e11bL/DKiBTUsrqs60gJHrYMwUAH+MifVZnixEWuDJtAUaHizbJ+yUPjH+9KxCoTxP2fWC34SOMGbAhiJ2uC9Vndb/zPmtI7m/oK9zplBQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FB9FP3Ze; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FB9FP3Ze" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A2534C4CEFB; Sat, 25 Oct 2025 16:27:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761409637; bh=674ScUfL2y2OnNZx6hSiuHRi3Sb7Jh74ZzdnAu96/C0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FB9FP3Ze/ksaLxYh9WIvnqxymo4lIUHCrh/1Xv4GFd7ZsJHLX9y0g5COqwLvWsS5/ +WBF/gMDBMXSlJd9vIeKEQX3mtuzEcRXC0Bn8yF7SZ+9lNw68IlbiEEejLHEMjs2QY nX90j8buf54dEEahRT3cKu1stpEuKLtJFd3CRg+WfhcW3r+JLgSqgJJyQJwQO9Rcjy 7+wmnUjht5zIOQ0CRAVb6xfU0Q5FrxwsIusqQPkvlojc6/JkSwuqOrvqC5n2vWVmWq hSL3h3FCL/yLkKlC4jtoApVyd27fc+Kg77x8a+ZkU5O2bkY7a3Dv04rfvL3HdMWLHA fkRjcaxoollzw== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Peter Wang , "Martin K. Petersen" , Sasha Levin , matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, linux-scsi@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 6.17-6.1] scsi: ufs: host: mediatek: Enhance recovery on resume failure Date: Sat, 25 Oct 2025 12:00:31 -0400 Message-ID: <20251025160905.3857885-400-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251025160905.3857885-1-sashal@kernel.org> References: <20251025160905.3857885-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.17.5 Content-Transfer-Encoding: 8bit From: Peter Wang [ Upstream commit 15ef3f5aa822f32524cba1463422a2c9372443f0 ] Improve the recovery process for failed resume operations. Log the device's power status and return 0 if both resume and recovery fail to prevent I/O hang. Signed-off-by: Peter Wang Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: YES Explanation - What changed (drivers/ufs/host/ufs-mediatek.c: fail path in `ufs_mtk_resume()`): - Old behavior: on resume failure, jump to `fail:` and return `ufshcd_link_recovery(hba)` (propagate error). - New behavior: at `fail:` call `ufshcd_link_recovery(hba)` and log runtime PM status if it fails; then unconditionally `return 0 /* Cannot return a failure, otherwise, the I/O will hang. */`. - Code reference: drivers/ufs/host/ufs-mediatek.c:1814 (call to `ufshcd_link_recovery(hba)`), followed by the new `dev_err()` that prints `hba->dev->power.request`, `runtime_status`, `runtime_error`, and the unconditional `return 0`. - Why this fixes a real bug affecting users (I/O hang): - The UFS core resume path calls the vendor resume first and bails out immediately if the vops `resume()` returns an error, skipping core recovery steps like hibern8 exit or full reset/restore: - Code reference: drivers/ufs/core/ufshcd.c:10011 (`ret = ufshcd_vops_resume(hba, pm_op); if (ret) goto out;`). - If the Mediatek variant previously returned an error from `ufs_mtk_resume()`, the core code would not attempt `ufshcd_uic_hibern8_exit()` or `ufshcd_reset_and_restore()`, leaving the link/device in a bad state and causing I/O to hang. - With this patch, the Mediatek driver tries `ufshcd_link_recovery()` locally and returns 0, allowing the core resume sequence to proceed: - If the link is in Hibern8, the core performs `ufshcd_uic_hibern8_exit()` (drivers/ufs/core/ufshcd.c:10025) and sets the link active. - If the link is off, the core performs `ufshcd_reset_and_restore()` (drivers/ufs/core/ufshcd.c:10034). - Hence, even if the vendor-specific parts hit an error, the core still executes its well-tested recovery and bring-up, which avoids the I/O hang scenario the commit message calls out. - Localized change, minimal risk: - The change is confined to one function in the Mediatek UFS host driver; no interface or architectural changes. - `ufshcd_link_recovery()` is the standard core recovery path for UFS (drivers/ufs/core/ufshcd.c:4467), which resets the device and host and is safe to invoke on failures. - Logging uses existing runtime PM fields for debugging and has no functional side effects. - Side effects considered: - Masking the error return from `ufshcd_link_recovery()` at the variant level does not hide failures overall: subsequent core steps will still return errors if the link/device is not brought back correctly, and the resume wrapper will report failure (drivers/ufs/core/ufshcd.c:10011+ path). - This approach improves robustness by ensuring core recovery always runs, which is preferable to aborting early and risking an unrecovered link and stuck I/O. - Stable backport criteria: - Fixes a user-visible bug (I/O hang after resume failures). - Patch is small, self-contained, and limited to Mediatek UFS host driver. - No new features or API changes; follows existing error-handling patterns (attempt recovery, proceed to core recovery, log details). - Low regression risk relative to the severity of the hang it prevents. Conclusion: This is a targeted bug fix that prevents I/O hangs by ensuring the core resume/recovery sequence runs even if the vendor resume fails. It is suitable for backporting to stable. drivers/ufs/host/ufs-mediatek.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/ufs/host/ufs-mediatek.c b/drivers/ufs/host/ufs-mediatek.c index bb0be6bed1bca..188f90e468c41 100644 --- a/drivers/ufs/host/ufs-mediatek.c +++ b/drivers/ufs/host/ufs-mediatek.c @@ -1727,8 +1727,21 @@ static int ufs_mtk_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op) } return 0; + fail: - return ufshcd_link_recovery(hba); + /* + * Check if the platform (parent) device has resumed, and ensure that + * power, clock, and MTCMOS are all turned on. + */ + err = ufshcd_link_recovery(hba); + if (err) { + dev_err(hba->dev, "Device PM: req=%d, status:%d, err:%d\n", + hba->dev->power.request, + hba->dev->power.runtime_status, + hba->dev->power.runtime_error); + } + + return 0; /* Cannot return a failure, otherwise, the I/O will hang. */ } static void ufs_mtk_dbg_register_dump(struct ufs_hba *hba) -- 2.51.0