Re: [PATCH] drm/tinydrm: Remove chunk splitting in tinydrm_spi_transfer

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, Feb 19, 2018 at 11:47:23AM +0000, Meghana Madhyastha wrote:
> -Remove chunk splitting in tinydrm_spi_transfer in tinydrm-helpers as The spi core will split a buffer into max_dma_len chunks for the
>  spi controller driver to handle.
> -Remove automatic byte swapping in tinydrm_spi_transfer as it doesn't have users.
> -Remove the upper bound check on dma transfer length in bcm2835_spi_can_dma().

This looks like a series of related changes that should be split up into
individual commits, probably at least one per bullet point there.

> -	/* BCM2835_SPI_DLEN has defined a max transfer size as
> -	 * 16 bit, so max is 65535
> -	 * we can revisit this by using an alternative transfer
> -	 * method - ideally this would get done without any more
> -	 * interaction...
> -	 */
> -	if (tfr->len > 65535) {
> -		dev_warn_once(&spi->dev,
> -			      "transfer size of %d too big for dma-transfer\n",
> -			      tfr->len);
> -		return false;
> -	}
> -

The changelog says we're removing this check but doesn't explain why
and...

>  	/* if we run rx/tx_buf with word aligned addresses then we are OK */
>  	if ((((size_t)tfr->rx_buf & 3) == 0) &&
>  	    (((size_t)tfr->tx_buf & 3) == 0))
> @@ -461,7 +448,7 @@ static void bcm2835_dma_init(struct spi_master *master, struct device *dev)
>  
>  	/* all went well, so set can_dma */
>  	master->can_dma = bcm2835_spi_can_dma;
> -	master->max_dma_len = 65535; /* limitation by BCM2835_SPI_DLEN */
> +	master->max_dma_len = 65528; /* limitation by BCM2835_SPI_DLEN */
>  	/* need to do TX AND RX DMA, so we need dummy buffers */
>  	master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;

...this bit of the change isn't mentioned at all?

Attachment: signature.asc
Description: PGP signature

_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Index of Archives]     [Linux DRI Users]     [Linux Intel Graphics]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux