Re: [PATCH 2/3] iwlagn: simplify iwlagn_tx_skb

["Guy, Wey-Yi" <wey-yi.w.guy@intel.com>]

On Fri, 2010-11-12 at 08:46 -0800, Stanislaw Gruszka wrote:
> Hi,
> 
> On Fri, Nov 12, 2010 at 07:52:05AM -0800, Guy, Wey-Yi wrote:
> > On Thu, 2010-11-11 at 23:47 -0800, Stanislaw Gruszka wrote:
> > > We can simplify length calculation in iwlagn_tx_skb, that function
> > > is enough complex, without fuzz it more than necessary.
> > > 
> > > Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
> > > ---
> > >  drivers/net/wireless/iwlwifi/iwl-agn-tx.c |   33 ++++++++++------------------
> > >  1 files changed, 12 insertions(+), 21 deletions(-)
> > > 
> > > diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-tx.c b/drivers/net/wireless/iwlwifi/iwl-agn-tx.c
> > > index 2b078a9..1205cec 100644
> > > --- a/drivers/net/wireless/iwlwifi/iwl-agn-tx.c
> > > +++ b/drivers/net/wireless/iwlwifi/iwl-agn-tx.c
> > > @@ -522,7 +522,7 @@ int iwlagn_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
> > >  	dma_addr_t phys_addr;
> > >  	dma_addr_t txcmd_phys;
> > >  	dma_addr_t scratch_phys;
> > > -	u16 len, len_org, firstlen, secondlen;
> > > +	u16 len, firstlen, secondlen;
> > >  	u16 seq_number = 0;
> > >  	__le16 fc;
> > >  	u8 hdr_len;
> > > @@ -687,30 +687,23 @@ int iwlagn_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
> > >  	 */
> > >  	len = sizeof(struct iwl_tx_cmd) +
> > >  		sizeof(struct iwl_cmd_header) + hdr_len;
> > > -
> > > -	len_org = len;
> > > -	firstlen = len = (len + 3) & ~3;
> > > -
> > > -	if (len_org != len)
> > > -		len_org = 1;
> > > -	else
> > > -		len_org = 0;
> > > +	firstlen = (len + 3) & ~3;
> > >  
> > >  	/* Tell NIC about any 2-byte padding after MAC header */
> > > -	if (len_org)
> > > +	if (firstlen != len)
> > >  		tx_cmd->tx_flags |= TX_CMD_FLG_MH_PAD_MSK;
> > >  
> > >  	/* Physical address of this Tx command's header (not MAC header!),
> > >  	 * within command buffer array. */
> > >  	txcmd_phys = pci_map_single(priv->pci_dev,
> > > -				    &out_cmd->hdr, len,
> > > +				    &out_cmd->hdr, firstlen,
> > >  				    PCI_DMA_BIDIRECTIONAL);
> > >  	dma_unmap_addr_set(out_meta, mapping, txcmd_phys);
> > > -	dma_unmap_len_set(out_meta, len, len);
> > > +	dma_unmap_len_set(out_meta, len, firstlen);
> > 
> > it is possible len != firstlen, right?
> 
> Yes it is, firstlen is aligned up to 4 byes value, txcmd_phys dma map
> size is firstlen and in consequence I use it every time with txcmd_phys.
> 
> > >  	/* Add buffer containing Tx command and MAC(!) header to TFD's
> > >  	 * first entry */
> > >  	priv->cfg->ops->lib->txq_attach_buf_to_tfd(priv, txq,
> > > -						   txcmd_phys, len, 1, 0);
> > > +						   txcmd_phys, firstlen, 1, 0);
> > >  
> > >  	if (!ieee80211_has_morefrags(hdr->frame_control)) {
> > >  		txq->need_update = 1;
> > > @@ -721,23 +714,21 @@ int iwlagn_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
> > >  
> > >  	/* Set up TFD's 2nd entry to point directly to remainder of skb,
> > >  	 * if any (802.11 null frames have no payload). */
> > > -	secondlen = len = skb->len - hdr_len;
> > > -	if (len) {
> > > +	secondlen = skb->len - hdr_len;
> > > +	if (secondlen > 0) {
> > >  		phys_addr = pci_map_single(priv->pci_dev, skb->data + hdr_len,
> > > -					   len, PCI_DMA_TODEVICE);
> > > +					   secondlen, PCI_DMA_TODEVICE);
> > >  		priv->cfg->ops->lib->txq_attach_buf_to_tfd(priv, txq,
> > > -							   phys_addr, len,
> > > +							   phys_addr, secondlen,
> > >  							   0, 0);
> > >  	}
> > >  
> > >  	scratch_phys = txcmd_phys + sizeof(struct iwl_cmd_header) +
> > >  				offsetof(struct iwl_tx_cmd, scratch);
> > >  
> > > -	len = sizeof(struct iwl_tx_cmd) +
> > > -		sizeof(struct iwl_cmd_header) + hdr_len;
> > >  	/* take back ownership of DMA buffer to enable update */
> > >  	pci_dma_sync_single_for_cpu(priv->pci_dev, txcmd_phys,
> > > -				    len, PCI_DMA_BIDIRECTIONAL);
> > > +				    firstlen, PCI_DMA_BIDIRECTIONAL);
> > 
> > same here, "firstlen" not necessary equal "len"
> 
> I guess its enough to sync just "len" but I prefer to use the
> size we used to map dma.
> 
ok, it make sense

Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>