On 13.09.2022 16:41:10, Rhett Aultman wrote:
> From: Vasanth Sadhasivan <vasanth.sadhasivan@xxxxxxxxxxx>
>
> DMA allocated buffers are a precious resource. If there is no need for DMA
> allocations, then it might be worth to use non-dma allocated buffers.
> After testing the gs_usb driver with and without DMA allocation, there
> does not seem to be a significant change in latency or cpu utilization
> either way. Therefore, DMA allocation is not necessary and removed.
>
> Co-developed-by: Rhett Aultman <rhett.aultman@xxxxxxxxxxx>
> Signed-off-by: Rhett Aultman <rhett.aultman@xxxxxxxxxxx>
> Signed-off-by: Vasanth Sadhasivan <vasanth.sadhasivan@xxxxxxxxxxx>
> ---
> drivers/net/can/usb/gs_usb.c | 38 ++++++++++--------------------------
> 1 file changed, 10 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
> index baf749c8cda3..1bfc775c62c5 100644
> --- a/drivers/net/can/usb/gs_usb.c
> +++ b/drivers/net/can/usb/gs_usb.c
> @@ -269,7 +269,6 @@ struct gs_can {
> struct usb_anchor tx_submitted;
> atomic_t active_tx_urbs;
> void *rxbuf[GS_MAX_RX_URBS];
> - dma_addr_t rxbuf_dma[GS_MAX_RX_URBS];
> };
>
> /* usb interface struct */
> @@ -587,9 +586,7 @@ static void gs_usb_xmit_callback(struct urb *urb)
>
> if (urb->status)
> netdev_info(netdev, "usb xmit fail %u\n", txc->echo_id);
> -
> - usb_free_coherent(urb->dev, urb->transfer_buffer_length,
> - urb->transfer_buffer, urb->transfer_dma);
> + devm_kfree(&urb->dev->dev, urb->transfer_buffer);
Consider using the URB_FREE_BUFFER flag:
| https://elixir.bootlin.com/linux/v5.19/source/include/linux/usb.h#L1330
and standard kmalloc() (i.e. not devm_kmalloc()). The USB stack will
take care of kfree()ing the buffer associated with each URB.
regards,
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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