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 0B7302F1FE2 for ; Tue, 1 Jul 2025 00:16:20 +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=1751328981; cv=none; b=BeSP/atONwLLa3yIW0Eu/w+vXYuOH3CC1rNvsSKYMGPWwKM5lbc19owGxM+jxPyf2YENV5gXCCDc+xnACjX2MilqfRtZkbn05IW5V3C7Wo245woPUA5lNoIuG6/j0XY/kUrwVY44pzpgzBg01SY/coC2MVSCgshrvQW3tulokPI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751328981; c=relaxed/simple; bh=yib31MXLzOGQnOJzci964+a5FAZ8uiJFxMZsY6ypURY=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wgfv78OijBjiFiNO3hLDvgtqITeGgJJ/WA9w/bZlfEza1x13gChdQuqC3amOBVzdLjE2bhPZpiywNtfgIHQGIx+5ejoebRCPv/zdGwYCoBkJ/FiEsmqde1JCqDw+GJ9lEKb4fjxKiBeGz5QRXvRxKFU1gdUV9y5BAiv8xJRSHrA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WvT4LlJo; 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="WvT4LlJo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 735A7C4CEF1; Tue, 1 Jul 2025 00:16:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751328980; bh=yib31MXLzOGQnOJzci964+a5FAZ8uiJFxMZsY6ypURY=; h=From:To:Subject:Date:In-Reply-To:References:From; b=WvT4LlJoR3UAI+x3tVM8wQVmIKaM1OZoB+8j5zhm4aeV1vYreOfTBtsyBp6GZVQGR YrTnEq7/BLV4QJ3nbn2fADLp+c5Idwg7KBgWKEwXCtyodCfdVUBNV45DqV78Qgsw9G Iup03RK66SIzK1TtQSoFX/VoACf8RLjx96puGPl6eJAQfu1AK9BZBt9bPqSCfTNO51 aPpjFwe9zVr5S0AqGpUJ61T3hdWP8+6S4aTUJm8e/bx8jZIS63qJYFPgMY5etLDDpc A7JkPZvQvPR8m//AF3A3cJXT9eWx/ZXHXDPxRT8Cajq0c0xj1kU5lhqcmK2pA24kx9 0+Gqdh2Hbal6Q== From: Damien Le Moal To: linux-ide@vger.kernel.org, Niklas Cassel Subject: [PATCH v2 04/10] ata: libata-eh: Avoid unnecessary resets when revalidating devices Date: Tue, 1 Jul 2025 09:14:02 +0900 Message-ID: <20250701001408.330364-5-dlemoal@kernel.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250701001408.330364-1-dlemoal@kernel.org> References: <20250701001408.330364-1-dlemoal@kernel.org> Precedence: bulk X-Mailing-List: linux-ide@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In ata_eh_revalidate_and_attach(), a link LPM policy is always set to ATA_LPM_MAX_POWER before calling ata_dev_revalidate() to ensure that the call to ata_phys_link_offline() does not return true, thus causing an unnecessary device reset. This change was introduced with commit 71d7b6e51ad3 ("ata: libata-eh: avoid needless hard reset when revalidating link"). However, setting the link LPM policy to ATA_LPM_MAX_POWER may be visible only after some time, depending on the power state the link was in. E.g. transitioning out of the Partial state should take no longer than a few microseconds, but transitioning out of the Slumber or DevSleep state may take several milliseconds. So despite the changes introduced with commit 71d7b6e51ad3 ("ata: libata-eh: avoid needless hard reset when revalidating link"), we can still endup with ata_phys_link_offline() seeing a link SCR_STATUS register signaling that the device is present (DET is equal to 1h) but that the link PHY is still in a low power mode (e.g. IPM is 2h, signaling "Interface in Partial power management state"). In such cases, ata_phys_link_offline() returns true, causing an EIO return for ata_eh_revalidate_and_attach() and a device reset. Avoid such unnecessary device resets by introducing a relaxed version of the link offline test implemented by ata_phys_link_offline() with the new helper function ata_eh_link_established(). This functions returns true if for the link SCR_STATUS register we see that: - A device is still present, that is, the DET field is 1h (Device presence detected but Phy communication not established) or 3h (Device presence detected and Phy communication established). - Communication is established, that is, the IPM field is not 0h, indicating that the PHY is online or in a low power state. Signed-off-by: Damien Le Moal Reviewed-by: Niklas Cassel --- drivers/ata/libata-eh.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c index f98d5123e1e4..7f5d13f9ca73 100644 --- a/drivers/ata/libata-eh.c +++ b/drivers/ata/libata-eh.c @@ -2071,6 +2071,33 @@ static void ata_eh_get_success_sense(struct ata_link *link) ata_eh_done(link, dev, ATA_EH_GET_SUCCESS_SENSE); } +/* + * Check if a link is established. This is a relaxed version of + * ata_phys_link_online() which accounts for the fact that this is potentially + * called after changing the link power management policy, which may not be + * reflected immediately in the SSTAUS register (e.g., we may still be seeing + * the PHY in partial, slumber or devsleep Partial power management state. + * So check that: + * - A device is still present, that is, DET is 1h (Device presence detected + * but Phy communication not established) or 3h (Device presence detected and + * Phy communication established) + * - Communication is established, that is, IPM is not 0h, indicating that PHY + * is online or in a low power state. + */ +static bool ata_eh_link_established(struct ata_link *link) +{ + u32 sstatus; + u8 det, ipm; + + if (sata_scr_read(link, SCR_STATUS, &sstatus)) + return false; + + det = sstatus & 0x0f; + ipm = (sstatus >> 8) & 0x0f; + + return (det & 0x01) && ipm; +} + /** * ata_eh_link_set_lpm - configure SATA interface power management * @link: link to configure @@ -3275,7 +3302,7 @@ static int ata_eh_revalidate_and_attach(struct ata_link *link, goto err; } - if (ata_phys_link_offline(ata_dev_phys_link(dev))) { + if (!ata_eh_link_established(ata_dev_phys_link(dev))) { rc = -EIO; goto err; } -- 2.50.0