From patchwork Thu May 2 04:02:46 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Weifeng Liu X-Patchwork-Id: 13651257 Received: from mail-pf1-f179.google.com (mail-pf1-f179.google.com [209.85.210.179]) (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 2C8721B299; Thu, 2 May 2024 04:03:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714622605; cv=none; b=o51KvV+FKpvm1c5dxeP2eXeg1ucveUksC3J2NKuBmPBSmYtPDPtDwAmoO3WuMUfGe5u5w6/Vhu0/bZeRiirBwUgwd35h1a+FvZ7ll/4Wv7VX/9rri4/ZCZ0AK3qK6veUXGnlVzC/k+GJbQxAkdUq8gmATDzUSozMlGLIzMSKswM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714622605; c=relaxed/simple; bh=h7tE368ohDcwrOQAQzkVk1DtOFsO1SY5csh/GFh4Txo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hhARSEuNdSjAtJOyb9wsJscXt+CYuGstts/EGZh6v18Wxky4Lc3aFgvs0Mmg0DXq+W2tBQwfsFaSUZwAPy+ha6Gf9YsniVtRW6pI4pN7B9nkTQbuSMta740Qko6083ushl4WK8hn/expBifK3nDSuGTw5POIFLkNwIWNpbvjr8k= 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=CaVzLHH0; arc=none smtp.client-ip=209.85.210.179 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="CaVzLHH0" Received: by mail-pf1-f179.google.com with SMTP id d2e1a72fcca58-6f4302187c0so377137b3a.1; Wed, 01 May 2024 21:03:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1714622603; x=1715227403; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=FnJuU2X/pt87elIj/zhh9UvoGxDEvntsc67nDMvs9CE=; b=CaVzLHH0f0kCdX5YuTIQmkaBhcVJ1K1uN+O9IoaojgzxpYOdU8fTIGQPbvSjPkXxUW ECoLc1BMZX+MaYVC9RGLehiKdQl8s/Rz/76KIrGygkpzfS5Uj51RmJO59075Ulwb9fv9 F6BcvLMfswfb5oc2HIReam7gtN5GIVg7huYmHbNIHgvyHzacR58fB5tWMP3jVVCt2/xK l40wjfoyCvmUPSikYRfYemeykwgg5f4nB+aZsk4jAFPj1O3rpPmW03S3qYs1xqkLrpkh ANRqHGg75I5HHLNwXaOKav5bNlpGQztbI+E6uQaiIhQ4XZEqRVvyfTVYems6UyPxSvr4 Uqiw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714622603; x=1715227403; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=FnJuU2X/pt87elIj/zhh9UvoGxDEvntsc67nDMvs9CE=; b=KLXp7XoD6EGaLw9UOeOcT9rIM5qIbDUiVBgmb74NH1Wx4nRGz6opkXAZmPuiZMM2q+ xB4qNTiccmqDfzpLwoMU/wUqjHMLom5Iio1O5WqUjgCEtkozOjaCxA8Z/AB5FODTEkj0 9uqK87uSIyGnCQMV5IFP5KFO6NQgOKC8ZKhzURnd9Noho7o6/zzjSgIGXHqXCv9uyPsy AWQiFTwknUCEe2pBzJ+xd6HXyGKk1Zov9p4AmKlt0ZvQzAZOHy58k1AYGn/eyp5o/HYp QXfJYt68EYAY1Z3hDi7OxMcz4RXQcO5dDJ6fEApMlrfZ2513LDiGWC4kI4JY03JJycNr STFw== X-Forwarded-Encrypted: i=1; AJvYcCW3+Z0RhTiMfMERqm6KFwhUOEiWZ1TX26uAfQVf+tnZxAn9FfzNgaeYTeaPshjTxZ6oyPm2Mn9bFoMdF6oTwhSwItofCCcR6F8rOa7n X-Gm-Message-State: AOJu0Yw1R2ZFefRNnq0x/HjmYi/+rUtrIm3j0tSeaGX04+ODCJ6boP5U Odb8trC8yGSloaYMKJnR8eI8zqeYLTkvEu3m8ryw5ggIDIgOtWR4wgfr2XprRhkyUWMw X-Google-Smtp-Source: AGHT+IGn4j4g9u9/GacxiHFcbFD4eOStwgvsekoIUj48l2bfdkYOs3d5lIsT4GtBL9BSvtkTtIr7rA== X-Received: by 2002:a05:6a20:2d23:b0:1a3:a821:f297 with SMTP id g35-20020a056a202d2300b001a3a821f297mr2373731pzl.2.1714622602952; Wed, 01 May 2024 21:03:22 -0700 (PDT) Received: from localhost ([103.192.225.104]) by smtp.gmail.com with ESMTPSA id g9-20020aa79dc9000000b006eae2d9298esm185842pfq.194.2024.05.01.21.03.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 May 2024 21:03:22 -0700 (PDT) From: Weifeng Liu To: platform-driver-x86@vger.kernel.org, linux-serial@vger.kernel.org Cc: Weifeng Liu , Maximilian Luz , Hans de Goede Subject: [RFC PATCH 1/2] platform/surface: aggregator: Defer probing when serdev is not ready Date: Thu, 2 May 2024 12:02:46 +0800 Message-ID: <20240502040255.655957-3-weifeng.liu.z@gmail.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240502040255.655957-2-weifeng.liu.z@gmail.com> References: <20240502040255.655957-2-weifeng.liu.z@gmail.com> Precedence: bulk X-Mailing-List: platform-driver-x86@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This is an attempt to alleviate race conditions in the SAM driver where essential resources like serial device and GPIO pins are not ready at the time ssam_serial_hub_probe() is called. Instead of giving up probing, a better way would be to defer the probing by returning -EPROBE_DEFER, allowing the kernel try again later. However, there is no way of identifying all such cases from other real errors in a few days. So let's take a gradual approach identify and address these cases as they arise. This commit marks the initial step in this process. Suggested-by: Maximilian Luz Signed-off-by: Weifeng Liu --- drivers/platform/surface/aggregator/core.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/platform/surface/aggregator/core.c b/drivers/platform/surface/aggregator/core.c index 9591a28bc38a..72a521dd729c 100644 --- a/drivers/platform/surface/aggregator/core.c +++ b/drivers/platform/surface/aggregator/core.c @@ -645,9 +645,20 @@ static int ssam_serial_hub_probe(struct serdev_device *serdev) /* Set up serdev device. */ serdev_device_set_drvdata(serdev, ctrl); serdev_device_set_client_ops(serdev, &ssam_serdev_ops); + + /* The following step can fail when it's called too early before the + * underlying uart device is ready (in this case -ENXIO is returned). + * Instead of simply giving up and losing everything, we can defer + * the probing by returning -EPROBE_DEFER so that the kernel would be + * able to retry later. */ status = serdev_device_open(serdev); - if (status) + if (status == -ENXIO) + status = -EPROBE_DEFER; + if (status) { + dev_err_probe(&serdev->dev, status, + "failed to open serdev device\n"); goto err_devopen; + } astatus = ssam_serdev_setup_via_acpi(ssh->handle, serdev); if (ACPI_FAILURE(astatus)) {