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Subject: Re: [PATCH] scsi: hisi_sas: Remove useless DMA-32 fallback
 configuration
To:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>
CC:     <linux-kernel@vger.kernel.org>, <kernel-janitors@vger.kernel.org>,
        <linux-scsi@vger.kernel.org>
References: <1bf2d3660178b0e6f172e5208bc0bd68d31d9268.1642237482.git.christophe.jaillet@wanadoo.fr>
From:   John Garry <john.garry@huawei.com>
Message-ID: <b7e68ce9-cca0-a5d7-0bd6-82cf597b9619@huawei.com>
Date:   Mon, 17 Jan 2022 09:28:06 +0000
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On 15/01/2022 09:05, Christophe JAILLET wrote:
> As stated in [1], dma_set_mask() with a 64-bit mask never fails if
> dev->dma_mask is non-NULL.
> So, if it fails, the 32 bits case will also fail for the same reason.
> 
> Simplify code and remove some dead code accordingly.
> 
> [1]: https://lore.kernel.org/linux-kernel/YL3vSPK5DXTNvgdx@infradead.org/#t
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Great, you got both callsites:

Acked-by: John Garry <john.garry@huawei.com>

> ---
>   drivers/scsi/hisi_sas/hisi_sas_main.c  | 3 ---
>   drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 2 --
>   2 files changed, 5 deletions(-)
> 
> diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
> index a05ec7aece5a..2f53a2ee024a 100644
> --- a/drivers/scsi/hisi_sas/hisi_sas_main.c
> +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
> @@ -2666,9 +2666,6 @@ static struct Scsi_Host *hisi_sas_shost_alloc(struct platform_device *pdev,
>   		goto err_out;
>   
>   	error = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
> -	if (error)
> -		error = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
> -
>   	if (error) {
>   		dev_err(dev, "No usable DMA addressing method\n");
>   		goto err_out;
> diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
> index a45ef9a5e12e..a01a3a7b706b 100644
> --- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
> +++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
> @@ -4695,8 +4695,6 @@ hisi_sas_v3_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>   		goto err_out;
>   
>   	rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
> -	if (rc)
> -		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
>   	if (rc) {
>   		dev_err(dev, "No usable DMA addressing method\n");
>   		rc = -ENODEV;
>