netdev - Re: [PATCH 1/4] b43legacy: remove b43legacy_dma_set

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Date:   Tue, 25 Jun 2019 16:45:51 -0500
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Christoph Hellwig <hch@....de>, Kalle Valo <kvalo@...eaurora.org>
Cc:     b43-dev@...ts.infradead.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] b43legacy: remove b43legacy_dma_set_mask

On 6/25/19 5:29 AM, Christoph Hellwig wrote:
> These days drivers are not required to fallback to smaller DMA masks,
> but can just set the largest mask they support, removing the need for
> this trial and error logic.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>   drivers/net/wireless/broadcom/b43legacy/dma.c | 39 +------------------
>   1 file changed, 1 insertion(+), 38 deletions(-)

The patches work for PPC32 for both b43legacy and b43.

Tested-by: Larry Finger <Larry.Finger@...inger.net>

Thanks,

Larry

> 
> diff --git a/drivers/net/wireless/broadcom/b43legacy/dma.c b/drivers/net/wireless/broadcom/b43legacy/dma.c
> index 2ce1537d983c..0c2de20622e3 100644
> --- a/drivers/net/wireless/broadcom/b43legacy/dma.c
> +++ b/drivers/net/wireless/broadcom/b43legacy/dma.c
> @@ -797,43 +797,6 @@ void b43legacy_dma_free(struct b43legacy_wldev *dev)
>   	dma->tx_ring0 = NULL;
>   }
>   
> -static int b43legacy_dma_set_mask(struct b43legacy_wldev *dev, u64 mask)
> -{
> -	u64 orig_mask = mask;
> -	bool fallback = false;
> -	int err;
> -
> -	/* Try to set the DMA mask. If it fails, try falling back to a
> -	 * lower mask, as we can always also support a lower one. */
> -	while (1) {
> -		err = dma_set_mask_and_coherent(dev->dev->dma_dev, mask);
> -		if (!err)
> -			break;
> -		if (mask == DMA_BIT_MASK(64)) {
> -			mask = DMA_BIT_MASK(32);
> -			fallback = true;
> -			continue;
> -		}
> -		if (mask == DMA_BIT_MASK(32)) {
> -			mask = DMA_BIT_MASK(30);
> -			fallback = true;
> -			continue;
> -		}
> -		b43legacyerr(dev->wl, "The machine/kernel does not support "
> -		       "the required %u-bit DMA mask\n",
> -		       (unsigned int)dma_mask_to_engine_type(orig_mask));
> -		return -EOPNOTSUPP;
> -	}
> -	if (fallback) {
> -		b43legacyinfo(dev->wl, "DMA mask fallback from %u-bit to %u-"
> -			"bit\n",
> -			(unsigned int)dma_mask_to_engine_type(orig_mask),
> -			(unsigned int)dma_mask_to_engine_type(mask));
> -	}
> -
> -	return 0;
> -}
> -
>   int b43legacy_dma_init(struct b43legacy_wldev *dev)
>   {
>   	struct b43legacy_dma *dma = &dev->dma;
> @@ -844,7 +807,7 @@ int b43legacy_dma_init(struct b43legacy_wldev *dev)
>   
>   	dmamask = supported_dma_mask(dev);
>   	type = dma_mask_to_engine_type(dmamask);
> -	err = b43legacy_dma_set_mask(dev, dmamask);
> +	err = dma_set_mask_and_coherent(dev->dev->dma_dev, dmamask);
>   	if (err) {
>   #ifdef CONFIG_B43LEGACY_PIO
>   		b43legacywarn(dev->wl, "DMA for this device not supported. "
>