From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f53.google.com (mail-wr1-f53.google.com [209.85.221.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 963F3307AE3 for ; Tue, 27 Jan 2026 15:41:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769528465; cv=none; b=N7l6WPV/N81XkGXzCERfxNzM3wg/wsQ560LYvb+mVPV/v1roo8QqZwUZjbSbJHQBcsFBb42ElgeaQ95nq3OYx+/VTdhn77fpyiZsAkeRCSCWCM2/zqPYfJF4e17of6jKAyeSSN+fp3J5f1N4XHeKsWH3wFPuVkZG19jNjSTsh54= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769528465; c=relaxed/simple; bh=aFDX34ybk/Kqa5bE8bFWwCkyvn6Pr2LS21JJKYV7n2Q=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Oe3bI016xSlY94vM9lB9Iy/lCBUL5TLBVXoBb2aeIlBi+ok79a0ggqFknay3k1wSxvv730oNnzwqw0Pxyj/gABDzfN7GrsnLc1s2Yw1X4MJ04G2q9p/fhRlIB7JEOe0pQdoS/8Y/WmSy1J7nnt7aaLChHqXmRLEHpvluo3LpT9g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=BvdYGu/G; arc=none smtp.client-ip=209.85.221.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BvdYGu/G" Received: by mail-wr1-f53.google.com with SMTP id ffacd0b85a97d-43246af170aso3452866f8f.0 for ; Tue, 27 Jan 2026 07:41:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769528462; x=1770133262; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=vxdGKRED/GezH50A93RC3QHz4tAJqHqw5Wvg3bxqlKY=; b=BvdYGu/Gu+/1coJYeMUpTSSjep1IUkzVucFjLs1c2A4yVxTC5GgmLOvTnDwlh0b/SP gTavINPyKus+OLbHsVxhvbL9v5aPMRqLWKW3qfUmFs9VPG6dQJBHOjksZibnR6t4b0R7 B2NOLg9xiOH8xDIZMA1SEsmv3X8vjkqUZJTn4YkGSR0z1yyvIA0qfGNv/Z9k6lwjdJGn MXyNfp7dtD4ajVllASm7vcylrrKNZ7JVNbgt2WOFSmyAOJr0AcN5pFGaq4O1C47qh0th dwQX9865EeUVIrB91YXtDXqtDZP7Uw6RlYXf8P9NNY8rZVlqKEmyh5lWyQahDUoOBrJy mD3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769528462; x=1770133262; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=vxdGKRED/GezH50A93RC3QHz4tAJqHqw5Wvg3bxqlKY=; b=P9yMJ4+ATkVb1spLqdJAAFgx8L3cE5POyzsHovNcTUYtguQ1wFz8jpfcS8FLefi9Yy uFbzaMPmD7Zt/y8mD5mOkl04DrbasHWZ2eYAglkP2kzJrIXow3noRTmvBkw+cM2DzWwf QWasfXFeBh9Ut4thqGjqCScUN+kwvtSJ34ZhM+GZ6M3Yb5pPt75vWLZpLk9eTRpf7XLr Hxqc5HA9SqiCaEOyJdWi2Gq64rOnJKT4zO59rwL3GI2IiGCQt70+mBm8lYGH0keKNOuP 0RDB1Wuy+tF6KZontKWtNtybiPtL4wDp+zhnnhQ+vd6YfRGoNfTN6TyPwzCUYRMWF5yU QbGg== X-Forwarded-Encrypted: i=1; AJvYcCX5zGtZsHZnUBj8oRDsZ3boBABcRCJO5h1ME/J0jWe9ZdfsFp2RURL9O2BHAxvPB66deqDvU/0yE42CHuyu@lists.linux.dev X-Gm-Message-State: AOJu0YyXTNgrZWc632yMxVxPY2HKsDBNEuO4oWwdH7c6BXF3g3A9mUm7 s9WlQUB8aPLYXnCeSLwxrg2wcrC9bRVD31z+qSpJ1snt7YXTHgDPDxh6 X-Gm-Gg: AZuq6aIMZZd+sNOgXkOtZj+JoWAlMq+8H+x7gUczbFTC/ztaVRZjiiJ4QRm8qwSIfA7 +QccsHtSvtGtaUbHhTjzAkb1YRa7VSC5eVJkS28voQ0nyyji+TYWJwRcCj96i2HP599KSnijydz W+ybfRfddOvS3wQGM3TuA7OEcvYS0F6sQOzdPe7OiA2xcGAQTL2wUlOh86OxTF6euSqhVFUmHHb /wB+n0GxqOOgrtbq1FJPUSYPGaQIgGevojY3akeR4rtheBwjWnqGcVFGXnrWEsHqsFc204Ccxdz iDMh5hEE9HMj8LBMlEAy9w+nVCPPf5kPHQQb/tEQxzV2lk6WdF2BPVfxqQBVDAppz8LUDh/13Ro xvyOfWgI2IQS6hgXhf7RXEGN9S4SoKEjOSXkkOX+070mgm7hyBUF3zW7Ukfvxsdu5jp+y0QmVS0 1KdZLEkJECCgfgUBlLiNk= X-Received: by 2002:a05:6000:1acc:b0:435:9538:939b with SMTP id ffacd0b85a97d-435dd0bdf07mr3190440f8f.8.1769528461541; Tue, 27 Jan 2026 07:41:01 -0800 (PST) Received: from Madhu.broadband ([83.106.123.52]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-435b1c0179bsm38451602f8f.1.2026.01.27.07.41.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jan 2026 07:41:01 -0800 (PST) From: Madhumitha Sundar To: sudipm.mukherjee@gmail.com, teddy.wang@siliconmotion.com, gregkh@linuxfoundation.org Cc: linux-fbdev@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, Madhumitha Sundar Subject: [PATCH v2] staging: sm750fb: replace magic number with jiffies timeout Date: Tue, 27 Jan 2026 15:40:56 +0000 Message-ID: <20260127154056.74855-1-madhuananda18@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The hardware wait loop in hw_sm750_de_wait used a hardcoded loop counter (0x10000000), which depends on CPU speed and is unreliable. Replace the loop counter with a jiffies-based timeout (1 second) using time_before(). This ensures consistent delays across architectures. Signed-off-by: Madhumitha Sundar --- Changes in v2: - Switched from loop counter to jiffies + cpu_relax() as requested by Greg KH. --- drivers/staging/sm750fb/sm750_hw.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/staging/sm750fb/sm750_hw.c b/drivers/staging/sm750fb/sm750_hw.c index ce46f240c..b24d27a77 100644 --- a/drivers/staging/sm750fb/sm750_hw.c +++ b/drivers/staging/sm750fb/sm750_hw.c @@ -523,19 +523,32 @@ int hw_sm750le_de_wait(void) int hw_sm750_de_wait(void) { - int i = 0x10000000; + /* Wait for 1 second (HZ) */ + unsigned long timeout = jiffies + HZ; unsigned int mask = SYSTEM_CTRL_DE_STATUS_BUSY | SYSTEM_CTRL_DE_FIFO_EMPTY | SYSTEM_CTRL_DE_MEM_FIFO_EMPTY; + unsigned int val; - while (i--) { - unsigned int val = peek32(SYSTEM_CTRL); + /* Run while Current Time is BEFORE the Deadline */ + while (time_before(jiffies, timeout)) { + val = peek32(SYSTEM_CTRL); + /* If Not Busy (0) AND Buffers Empty (1), we are good */ if ((val & mask) == (SYSTEM_CTRL_DE_FIFO_EMPTY | SYSTEM_CTRL_DE_MEM_FIFO_EMPTY)) return 0; + + /* Polite pause to save power */ + cpu_relax(); } - /* timeout error */ + + /* Final check in case we succeeded at the last millisecond */ + val = peek32(SYSTEM_CTRL); + if ((val & mask) == + (SYSTEM_CTRL_DE_FIFO_EMPTY | SYSTEM_CTRL_DE_MEM_FIFO_EMPTY)) + return 0; + return -1; } -- 2.43.0