Message-ID: <b9bc20f3-cf68-6546-1979-6b36f622913f@acm.org>
Date:   Wed, 1 Feb 2023 09:20:39 -0800
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Subject: Re: [PATCH] scsi: ufs: core: Limit DMA alignment check
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To:     Bjorn Andersson <quic_bjorande@quicinc.com>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Asutosh Das <quic_asutoshd@quicinc.com>
Cc:     Bean Huo <beanhuo@micron.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Jinyoung Choi <j-young.choi@samsung.com>,
        linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, mani@kernel.org
References: <20230201034917.1902330-1-quic_bjorande@quicinc.com>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <20230201034917.1902330-1-quic_bjorande@quicinc.com>
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On 1/31/23 19:49, Bjorn Andersson wrote:
> The three DMA memory regions allocated for the host memory space is
> documented to require alignment of 128, 1024 and 1024 respectively, but
> the returned address is checked for PAGE_SIZE alignment.
> 
> In the case these allocations are serviced by e.g. the Arm SMMU, the
> size and alignment will be determined by its supported page sizes. In
> most cases SZ_4K and a few larger sizes are available.
> 
> In the typical configuration this does not cause problems, but in the
> event that the system PAGE_SIZE is increased beyond 4k, it's no longer
> reasonable to expect that the allocation will be PAGE_SIZE aligned.
> 
> Limit the DMA alignment check to the actual alignment requirements
> written in the comments in the code, to avoid the UFS core refusing to
> initialize with such configuration.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>