Subject: Re: [PATCH 2/3] Blackfin EMAC Driver: enable TXDWA new feature for new silicon (rev > 0.2)

From: Ingo Oeser <[email-masked]>
Date: Mon, 28 Jul 2008 12:05:36 +0200

Hi Bryan,

you duplicate a lot of clever code here. 
Would you mind refactoring this part in a follow-up patch?

Bryan Wu schrieb:
> Signed-off-by: Bryan Wu <[email-masked]>
> ---
>  drivers/net/bfin_mac.c |  103 ++++++++++++++++++++++++++++++++++++------------
>  1 files changed, 77 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/net/bfin_mac.c b/drivers/net/bfin_mac.c
> index e18a7ee..57ebe6d 100644
> --- a/drivers/net/bfin_mac.c
> +++ b/drivers/net/bfin_mac.c
> @@ -606,36 +606,87 @@ adjust_head:
>  static int bfin_mac_hard_start_xmit(struct sk_buff *skb,
>  				struct net_device *dev)
>  {
> -	unsigned int data;
> +	u16 *data;
>  
>  	current_tx_ptr->skb = skb;
>  
> -	/*
> -	 * Is skb->data always 16-bit aligned?
> -	 * Do we need to memcpy((char *)(tail->packet + 2), skb->data, len)?
> -	 */
> -	if ((((unsigned int)(skb->data)) & 0x01) == 0) {
> -		/* move skb->data to current_tx_ptr payload */
> -		data = (unsigned int)(skb->data) - 2;
> -		*((unsigned short *)data) = (unsigned short)(skb->len);
> -		current_tx_ptr->desc_a.start_addr = (unsigned long)data;
> -		/* this is important! */
> -		blackfin_dcache_flush_range(data, (data + (skb->len)) + 2);
> -
> +	if (ANOMALY_05000285) {
> +		/*
> +		 * TXDWA feature is not avaible to older revision < 0.3 silicon
> +		 * of BF537
> +		 *
> +		 * Only if data buffer is ODD WORD alignment, we do not
> +		 * need to memcpy
> +		 */
> +		u32 data_align = (u32)(skb->data) & 0x3;
> +		if (data_align == 0x2) {
> +			/* move skb->data to current_tx_ptr payload */
> +			data = (u16 *)(skb->data) - 1;
> +			*data = (u16)(skb->len);
> +			current_tx_ptr->desc_a.start_addr = (u32)data;
> +			/* this is important! */
> +			blackfin_dcache_flush_range((u32)data,
> +					(u32)((u8 *)data + skb->len + 4));
> +		} else {
> +			*((u16 *)(current_tx_ptr->packet)) = (u16)(skb->len);
> +			memcpy((u8 *)(current_tx_ptr->packet + 2), skb->data,
> +				skb->len);
> +			current_tx_ptr->desc_a.start_addr =
> +				(u32)current_tx_ptr->packet;
> +			if (current_tx_ptr->status.status_word != 0)
> +				current_tx_ptr->status.status_word = 0;
> +			blackfin_dcache_flush_range(
> +				(u32)current_tx_ptr->packet,
> +				(u32)(current_tx_ptr->packet + skb->len + 2));
> +		}
>  	} else {
> -		*((unsigned short *)(current_tx_ptr->packet)) =
> -		    (unsigned short)(skb->len);
> -		memcpy((char *)(current_tx_ptr->packet + 2), skb->data,
> -		       (skb->len));
> -		current_tx_ptr->desc_a.start_addr =
> -		    (unsigned long)current_tx_ptr->packet;
> -		if (current_tx_ptr->status.status_word != 0)
> -			current_tx_ptr->status.status_word = 0;
> -		blackfin_dcache_flush_range((unsigned int)current_tx_ptr->
> -					    packet,
> -					    (unsigned int)(current_tx_ptr->
> -							   packet + skb->len) +
> -					    2);
> +		/*
> +		 * TXDWA feature is avaible to revision < 0.3 silicon of
> +		 * BF537 and always avaible to BF52x
> +		 */
> +		u32 data_align = (u32)(skb->data) & 0x3;
> +		if (data_align == 0x0) {

This condition seems to be the only part dependend on "ANOMALY_05000285".

> +			u16 sysctl = bfin_read_EMAC_SYSCTL();
> +			sysctl |= TXDWA;
> +			bfin_write_EMAC_SYSCTL(sysctl);
> +
> +			/* move skb->data to current_tx_ptr payload */
> +			data = (u16 *)(skb->data) - 2;
> +			*data = (u16)(skb->len);
> +			current_tx_ptr->desc_a.start_addr = (u32)data;
> +			/* this is important! */
> +			blackfin_dcache_flush_range(
> +					(u32)data,
> +					(u32)((u8 *)data + skb->len + 4));
> +		} else if (data_align == 0x2) {
> +			u16 sysctl = bfin_read_EMAC_SYSCTL();
> +			sysctl &= ~TXDWA;
> +			bfin_write_EMAC_SYSCTL(sysctl);
> +
> +			/* move skb->data to current_tx_ptr payload */
> +			data = (u16 *)(skb->data) - 1;
> +			*data = (u16)(skb->len);
> +			current_tx_ptr->desc_a.start_addr = (u32)data;
> +			/* this is important! */
> +			blackfin_dcache_flush_range(
> +					(u32)data,
> +					(u32)((u8 *)data + skb->len + 4));
> +		} else {
> +			u16 sysctl = bfin_read_EMAC_SYSCTL();
> +			sysctl &= ~TXDWA;
> +			bfin_write_EMAC_SYSCTL(sysctl);
> +
> +			*((u16 *)(current_tx_ptr->packet)) = (u16)(skb->len);
> +			memcpy((u8 *)(current_tx_ptr->packet + 2), skb->data,
> +				skb->len);
> +			current_tx_ptr->desc_a.start_addr =
> +				(u32)current_tx_ptr->packet;
> +			if (current_tx_ptr->status.status_word != 0)
> +				current_tx_ptr->status.status_word = 0;
> +			blackfin_dcache_flush_range(
> +				(u32)current_tx_ptr->packet,
> +				(u32)(current_tx_ptr->packet + skb->len + 2));
> +		}
>  	}
>  
>  	/* enable this packet's dma */

Best Regards

Ingo Oeser