linux-kernel - RE: [PATCH] mei: me: Use dma_set_mask_and

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Date:   Sun, 9 Jan 2022 06:05:35 +0000
From:   "Winkler, Tomas" <tomas.winkler@...el.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        "arnd@...db.de" <arnd@...db.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
        "Usyskin, Alexander" <alexander.usyskin@...el.com>
Subject: RE: [PATCH] mei: me: Use dma_set_mask_and_coherent() and simplify
 code


> 
> Use dma_set_mask_and_coherent() instead of unrolling it with some
> dma_set_mask()+dma_set_coherent_mask().
> 
> Moreover, as stated in [1], dma_set_mask() with a 64-bit mask will never fail
> 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.
> 
> 
> While at it, include directly <linux/dma-mapping.h> instead on relying on
> indirect inclusion.
> 
> [1]: https://lkml.org/lkml/2021/6/7/398
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Acked-by: Tomas Winkler <tomas.winkler@...el.com>
> ---
>  drivers/misc/mei/pci-me.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/misc/mei/pci-me.c b/drivers/misc/mei/pci-me.c index
> 3a45aaf002ac..a05cdb25d0c4 100644
> --- a/drivers/misc/mei/pci-me.c
> +++ b/drivers/misc/mei/pci-me.c
> @@ -10,6 +10,7 @@
>  #include <linux/errno.h>
>  #include <linux/types.h>
>  #include <linux/pci.h>
> +#include <linux/dma-mapping.h>
>  #include <linux/sched.h>
>  #include <linux/interrupt.h>
> 
> @@ -192,14 +193,7 @@ static int mei_me_probe(struct pci_dev *pdev,
> const struct pci_device_id *ent)
>  		goto end;
>  	}
> 
> -	if (dma_set_mask(&pdev->dev, DMA_BIT_MASK(64)) ||
> -	    dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64))) {
> -
> -		err = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
> -		if (err)
> -			err = dma_set_coherent_mask(&pdev->dev,
> -						    DMA_BIT_MASK(32));
> -	}
> +	err = dma_set_mask_and_coherent(&pdev->dev,
> DMA_BIT_MASK(64));
>  	if (err) {
>  		dev_err(&pdev->dev, "No usable DMA configuration,
> aborting\n");
>  		goto end;
> --
> 2.32.0