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 4488C3ACF16; Thu, 19 Mar 2026 11:07:10 +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=1773918431; cv=none; b=nlgFctWo/7i//oLZJcvzo52wmfrEMFUpb5gPqgFQCnnjcpBDF/7dg6ebhZvJPpQXADHm2UKAM3mT7BkHcN7nG/YThSdKdp/drrdsUrJLw0Fotq+Yd/Gbes07WKbA0h624bmYY0x6VLOsSqiEJLIjjiidCW4DbozzQGKFmRf4+VU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773918431; c=relaxed/simple; bh=d+AJOiDuQJDfnt3iYqZ+1afaE7nwYUax5zKgGgxWn7g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eDqIDVpryRMyGscN/iT5o8PLH3cTE13PT4TLjxgdalonG939Lvnw6DhX1Gt5JIyPK35NP15CKPobo3ePXsKukIbmypAeGvjBV3ron5NHgdLe39iCg95WuQjVanh6DdkrzR/Krql5AhedyGtPlop9GDiDH2qRfcpbeuRvDznqEG4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cv/hPJlu; 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="cv/hPJlu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF796C19424; Thu, 19 Mar 2026 11:07:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773918430; bh=d+AJOiDuQJDfnt3iYqZ+1afaE7nwYUax5zKgGgxWn7g=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cv/hPJlua64GSjb35XUhLuo8MGoU2r2Uj+KQ+FQ5AixyiE7P02wWhe/4afp5pOmdf 1AKTYTj/ETlPuzKz4hmhjsers3l0MLoSSeyWpvD0emzhmzDYdlStCnmWg3AoJE2ZNt q/20rAbNMBPA29OlFnHcGtCwzX1repGdx5TZH/5gJ8Pruf1ncPbjJBrruPwKrlkk7C sdtp9l6e+hS5KwsKyAscu9nWBcWHe48Ht9wGkmjcmolAvAnPCJqLXuvXSP3+pheNte J08mMZc0H9fMWbV6qhWnQqFFl2oXOzpd6WFvcrYmBcs7nlo1CZpzYTrMA1GnylBrA7 aKw2JflaH6iEw== Message-ID: <6a78fcaa-7a3e-423f-b6f5-84cd66a3c88f@kernel.org> Date: Thu, 19 Mar 2026 20:07:07 +0900 Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] scsi: sas: skip opt_sectors when DMA reports no real optimization hint To: "Ionut Nechita (Wind River)" , linux-scsi@vger.kernel.org Cc: James.Bottomley@HansenPartnership.com, ahuang12@lenovo.com, axboe@kernel.dk, hch@lst.de, ionut_n2001@yahoo.com, john.g.garry@oracle.com, linux-kernel@vger.kernel.org, m.szyprowski@samsung.com, martin.petersen@oracle.com, robin.murphy@arm.com, sunlightlinux@gmail.com References: <20260319083954.21056-1-ionut.nechita@windriver.com> <20260319083954.21056-2-ionut.nechita@windriver.com> Content-Language: en-US From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <20260319083954.21056-2-ionut.nechita@windriver.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/19/26 17:39, Ionut Nechita (Wind River) wrote: > +static unsigned int sas_dma_opt_sectors(struct device *dma_dev, > + unsigned int max_sectors) > +{ > + size_t opt = dma_opt_mapping_size(dma_dev); > + size_t max = dma_max_mapping_size(dma_dev); > + > + if (WARN_ONCE(opt > max, > + "dma_opt_mapping_size (%zu) > dma_max_mapping_size (%zu)\n", > + opt, max)) > + return 0; > + > + if (opt == max) > + return 0; Why return 0 ? This is a valid case, so this should get through the alignment below. > + > + opt = rounddown_pow_of_two(opt); > + > + return min_t(unsigned int, opt >> SECTOR_SHIFT, max_sectors); > +} > + -- Damien Le Moal Western Digital Research