Re: [PATCH 3/4] mt76: speed up usb bulk copy

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> Use larger batches for usb copy to speed this operation up. Otherwise it
> would be too slow for copying new beacons or broadcast frames over usb.
> 
> Signed-off-by: Markus Theil <markus.theil@tu-ilmenau.de>
> ---

Hi Markus,

>  drivers/net/wireless/mediatek/mt76/mt76.h     |  2 +-
>  .../wireless/mediatek/mt76/mt76x02_beacon.c   |  1 -
>  drivers/net/wireless/mediatek/mt76/usb.c      | 22 ++++++++++++++-----
>  3 files changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
> index 8aec7ccf2d79..7a6f5d097a3d 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76.h
> +++ b/drivers/net/wireless/mediatek/mt76/mt76.h
> @@ -383,7 +383,7 @@ enum mt76u_out_ep {
>  struct mt76_usb {
>  	struct mutex usb_ctrl_mtx;
>  	union {
> -		u8 data[32];
> +		u8 data[128];
>  		__le32 reg_val;
>  	};
>  
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c b/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c
> index 47207b790bf9..8b2f7a0d58b5 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c
> @@ -86,7 +86,6 @@ int mt76x02_mac_set_beacon(struct mt76x02_dev *dev, u8 vif_idx,
>  	dev->beacons[vif_idx] = skb;
>  	__mt76x02_mac_set_beacon(dev, vif_idx, skb);
>  
> -
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(mt76x02_mac_set_beacon);
> diff --git a/drivers/net/wireless/mediatek/mt76/usb.c b/drivers/net/wireless/mediatek/mt76/usb.c
> index 20c6fe510e9d..6183105166ec 100644
> --- a/drivers/net/wireless/mediatek/mt76/usb.c
> +++ b/drivers/net/wireless/mediatek/mt76/usb.c
> @@ -149,18 +149,28 @@ static void mt76u_copy(struct mt76_dev *dev, u32 offset,
>  		       const void *data, int len)
>  {
>  	struct mt76_usb *usb = &dev->usb;
> -	const u32 *val = data;
> -	int i, ret;
> +	const u8 *val = data;
> +	int ret;
> +	const int batch_size_max = sizeof(usb->data);
> +	int current_batch_size;
> +	int i = 0;
>  
>  	mutex_lock(&usb->usb_ctrl_mtx);
> -	for (i = 0; i < DIV_ROUND_UP(len, 4); i++) {
> -		put_unaligned(val[i], (u32 *)usb->data);
> +	while (i < len) {
> +		if(len - i > batch_size_max) {
> +			current_batch_size = batch_size_max;
> +		} else {
> +			current_batch_size = len - i;
> +		}

		current_batch_size = min(sizeof(usb->data), len - i);

> +		memcpy(usb->data, val + i, current_batch_size);
>  		ret = __mt76u_vendor_request(dev, MT_VEND_MULTI_WRITE,
>  					     USB_DIR_OUT | USB_TYPE_VENDOR,
> -					     0, offset + i * 4, usb->data,
> -					     sizeof(u32));
> +					     0, offset + i, usb->data,
> +					     current_batch_size);

@Stanislaw: I vaguely remember you reported some issues if the burst size 
is greater than 4B (but I can be wrong)

>  		if (ret < 0)
>  			break;
> +
> +		i += current_batch_size;
>  	}
>  	mutex_unlock(&usb->usb_ctrl_mtx);
>  }
> -- 
> 2.24.0
> 

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