From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (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 20DF41E0096; Wed, 6 Nov 2024 13:29:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730899774; cv=none; b=db/2n/vidzGsdaztAukbk655A/qKbVK57mDwVWu+gwFOFfEuEF9Az5LZEUFcFCUigM1+nah1anjune72ZnxpL+cVcWCj1nBZ2byvvrtzT2hLmTs/e7nVsZifmxqklSLVZ0alTTfIlib2QdQfJg6ZFHK76PNseoXWwQZn+qXHsMs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730899774; c=relaxed/simple; bh=fVNkLpFzLkJsXQDVFwWhgGwWb8WzrbwjQ1RM/7ZwYPg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=KO2X2LrliGtim4h3GbOMerwUG91mMeX6E+3P0hBbyqj0+aeiTpKatXfakFdcw1dm9rABvUl3P5EK6uSK4Apf1eNDaWeT7YhAo7qkP6+bD8uFW+CdCp5Z5r0ANRWw9EVJhqoywiR7QodqJodlHqPYgQfPeehK0NxKN8MTwBjCupg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=AVJoO+oe; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="AVJoO+oe" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1730899770; bh=fVNkLpFzLkJsXQDVFwWhgGwWb8WzrbwjQ1RM/7ZwYPg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=AVJoO+oeMmm6+03UpFQIcu/uxg08bLNLx3b7YD2da7REpGSSjwKsSCYY9orX7+GLa +lEPCi5Wa3UjHuyTQuDiE+qUuIRHPefudnng2qA5oVp/NObxK2okD+nu4KW8raVwPA Ru8ku58XniWkPi0/f3AH5ZQWfPm8IubNRnTdIpf6hLESLuGRLYi+JWSnfpZVjLvNv3 yUiYriF2uZhLxtpG2jl9rLQGmPoNkO94ickQYhoKkW3SKLeefU54klvGizPyMFKC1Y cvWPhVTrnbzVACKrdK2tBGK/iDvOp1fE7KTDaA71YrmhLbk27D95OmIbHk7DuuFDQe oMQtWCMeVGMJg== Received: from [192.168.1.100] (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) (Authenticated sender: kholk11) by bali.collaboradmins.com (Postfix) with ESMTPSA id C6A2F17E3637; Wed, 6 Nov 2024 14:29:29 +0100 (CET) Message-ID: Date: Wed, 6 Nov 2024 14:29:29 +0100 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/2] PCI: mediatek-gen3: Add support for restricting link width To: =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= Cc: linux-pci@vger.kernel.org, ryder.lee@mediatek.com, jianjun.wang@mediatek.com, lpieralisi@kernel.org, robh@kernel.org, bhelgaas@google.com, matthias.bgg@gmail.com, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel@collabora.com, fshao@chromium.org, Manivannan Sadhasivam References: <20241104114935.172908-1-angelogioacchino.delregno@collabora.com> <20241104114935.172908-3-angelogioacchino.delregno@collabora.com> <20241104132046.GA2504924@rocinante> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: <20241104132046.GA2504924@rocinante> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Il 04/11/24 14:20, Krzysztof Wilczyński ha scritto: > > Hello, > >> + ret = of_property_read_u32(dev->of_node, "num-lanes", &num_lanes); >> + if (ret == 0) { >> + if (num_lanes == 0 || num_lanes > 16 || (num_lanes != 1 && num_lanes % 2)) >> + dev_warn(dev, "Invalid num-lanes, using controller defaults\n"); >> + else >> + pcie->num_lanes = num_lanes; >> + } >> + >> return 0; >> } > > If you were to handle non-zero return value as an error here, perhaps the > property has not been set, then we could reduce the indentation here. > > Something like this, perhaps? > > ret = of_property_read_u32(dev->of_node, "num-lanes", &num_lanes); > if (ret) { > dev_err(dev, "Failed to read num-lanes: %d\n", ret); > return ret; > } > > if (!num_lanes || num_lanes > 16 || (num_lanes != 1 && num_lanes % 2)) > dev_warn(dev, "Invalid num-lanes, using controller defaults\n"); > else > pcie->num_lanes = num_lanes; > > Does this make sense here? Thoughts? > > Krzysztof Sorry I've just seen this email. There's a problem here: this property has to be optional - and if you change that to return like that, you're breaking compatibility with older device trees, which are not specifying any "num-lanes" property. Please remember that of_property_read_u32() returns: - 0 on success - -EINVAL if the property does not exist - -ENODATA or -EOVERFLOW Please either keep the error checking like I wrote, or alternatively you can do.. ret = of_property_read_u32(...) if (ret != -EINVAL) { dev_err(dev, "Failed to read num-lanes: %d\n", ret); return ret; } else { if (num_lanes == 0 || ..... etc etc) dev_warn() else pcie->num_lanes = num_lanes } Cheers, Angelo