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Fri, 13 Nov 2026 22:18:28 -0800 (PST) Received: from ryzen.lan ([2601:644:8000:37f::e34]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-37955e0d966sm13200536eec.15.2026.11.13.22.18.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Nov 2026 22:18:27 -0800 (PST) From: Rosen Penev To: Stuart Hayes , Hans de Goede , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Doug Warzecha , Andrew Morton , Andy Shevchenko Cc: platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 5/5] platform/x86: dell: dcdbas: Use read_poll_timeout_atomic() for the type 1 SMI Date: Fri, 13 Nov 2026 22:17:58 -0800 Message-ID: <6380dadbc5d515b4ce0d3322210ac44e4d541200.1794633178.git.rosenp@gmail.com> X-Mailer: git-send-email 2.56.1 In-Reply-To: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit For SMI type 1, host_control_smi() polls the APM status port in a loop that counts down TIMEOUT_USEC_SHORT_SEMA_BLOCKING iterations and relies on each inb() taking about a microsecond. Use read_poll_timeout_atomic() with a 1us delay instead, like the type 2 and 3 path, so the timeout is in microseconds and does not depend on how long a port read takes. With the delay plus the port read, the worst-case wait grows from about 10ms to about 20ms, which only matters when the BIOS never answers. This removes the last users of num_ticks and EXPIRED_TIMER. Signed-off-by: Rosen Penev --- drivers/platform/x86/dell/dcdbas.c | 12 +++++------- drivers/platform/x86/dell/dcdbas.h | 1 - 2 files changed, 5 insertions(+), 8 deletions(-) diff --git a/drivers/platform/x86/dell/dcdbas.c b/drivers/platform/x86/dell/dcdbas.c index af4c1d2fe497..edc210852f2d 100644 --- a/drivers/platform/x86/dell/dcdbas.c +++ b/drivers/platform/x86/dell/dcdbas.c @@ -394,7 +394,6 @@ static int host_control_smi(void) struct apm_cmd *apm_cmd; u8 *data; unsigned long flags; - u32 num_ticks; s8 cmd_status; u8 index; @@ -424,12 +423,11 @@ static int host_control_smi(void) spin_unlock_irqrestore(&rtc_lock, flags); /* wait a few to see if it executed */ - num_ticks = TIMEOUT_USEC_SHORT_SEMA_BLOCKING; - while ((s8)inb(PCAT_APM_STATUS_PORT) == ESM_STATUS_CMD_UNSUCCESSFUL) { - num_ticks--; - if (num_ticks == EXPIRED_TIMER) - return -ETIME; - } + if (read_poll_timeout_atomic(inb, cmd_status, + cmd_status != ESM_STATUS_CMD_UNSUCCESSFUL, + 1, TIMEOUT_USEC_SHORT_SEMA_BLOCKING, + false, PCAT_APM_STATUS_PORT)) + return -ETIME; break; case HC_SMITYPE_TYPE2: diff --git a/drivers/platform/x86/dell/dcdbas.h b/drivers/platform/x86/dell/dcdbas.h index a05d7f667586..d5ad2363dd9e 100644 --- a/drivers/platform/x86/dell/dcdbas.h +++ b/drivers/platform/x86/dell/dcdbas.h @@ -42,7 +42,6 @@ #define MAX_SYSMGMT_LONGCMD_SGENTRY_NUM (16) #define TIMEOUT_USEC_SHORT_SEMA_BLOCKING (10000) -#define EXPIRED_TIMER (0) #define SMI_CMD_MAGIC (0x534D4931) #define SMM_EPS_SIG "$SCB" -- 2.56.0