linux-kernel - Re: [PATCH v2] crypto: ccree - Remove a useless dma

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Message-ID: <CAOtvUMe3AFbKUCR4L3=Zm9_UxVJNRqxjcU+CR5LHG3B=y839fg@mail.gmail.com>
Date:   Wed, 20 Jul 2022 18:31:27 +0300
From:   Gilad Ben-Yossef <gilad@...yossef.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Linux kernel mailing list <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        Christoph Hellwig <hch@...radead.org>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: Re: [PATCH v2] crypto: ccree - Remove a useless dma_supported() call

Hi,


On Wed, Jul 20, 2022 at 4:29 PM Christophe JAILLET
<christophe.jaillet@...adoo.fr> wrote:
>
> There is no point in calling dma_supported() before calling
> dma_set_coherent_mask(). This function already calls dma_supported() and
> returns an error (-EIO) if it fails.
>
> So remove the superfluous dma_supported() call.
>
> Moreover, setting a larger DMA mask will never fail when setting a smaller
> one will succeed, so the whole "while" loop can be removed as well. (see
> [1])
>
> While at it, fix the name of the function reported in a dev_err().
>
> [1]: https://lore.kernel.org/all/YteQ6Vx2C03UtCkG@infradead.org/
>
> Suggested-by: Christoph Hellwig <hch@...radead.org>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
>  drivers/crypto/ccree/cc_driver.c | 13 +++----------
>  1 file changed, 3 insertions(+), 10 deletions(-)

Acked-by: Gilad Ben-Yossef <gilad@...yossef.com>

Thank you,
Gilad

>
> diff --git a/drivers/crypto/ccree/cc_driver.c b/drivers/crypto/ccree/cc_driver.c
> index 7d1bee86d581..cadead18b59e 100644
> --- a/drivers/crypto/ccree/cc_driver.c
> +++ b/drivers/crypto/ccree/cc_driver.c
> @@ -372,17 +372,10 @@ static int init_cc_resources(struct platform_device *plat_dev)
>                 dev->dma_mask = &dev->coherent_dma_mask;
>
>         dma_mask = DMA_BIT_MASK(DMA_BIT_MASK_LEN);
> -       while (dma_mask > 0x7fffffffUL) {
> -               if (dma_supported(dev, dma_mask)) {
> -                       rc = dma_set_coherent_mask(dev, dma_mask);
> -                       if (!rc)
> -                               break;
> -               }
> -               dma_mask >>= 1;
> -       }
> -
> +       rc = dma_set_coherent_mask(dev, dma_mask);
>         if (rc) {
> -               dev_err(dev, "Failed in dma_set_mask, mask=%llx\n", dma_mask);
> +               dev_err(dev, "Failed in dma_set_coherent_mask, mask=%llx\n",
> +                       dma_mask);
>                 return rc;
>         }
>
> --
> 2.34.1
>


-- 
Gilad Ben-Yossef
Chief Coffee Drinker

values of β will give rise to dom!