Re: [linux-nfc] [PATCH 1/2] NFC: Remove crc generation from shdlc layer

[Rymarkiewicz Waldemar <waldemar.rymarkiewicz@tieto.com>]

Hi Eric,

> As a side effect of my comment on the second patch, this should be
> defined like this:
>
>   #define PN544_CMDS_HEADROOM	2
> +#define PN544_FRAME_HEADROOM	1
> +#define PN544_FRAME_TAILROOM	2
>
>>>   static int pn544_hci_xmit(struct nfc_shdlc *shdlc, struct sk_buff *skb)
>>>   {
>>>   	struct pn544_hci_info *info = nfc_shdlc_get_clientdata(shdlc);
>>> @@ -584,6 +599,8 @@ static int pn544_hci_xmit(struct nfc_shdlc
> *shdlc, struct sk_buff *skb)
>>>   	if (info->hard_fault != 0)
>>>   		return info->hard_fault;
>>>
>>> +	pn544_hci_add_len_crc(skb);
>>> +
>>>   	return pn544_hci_i2c_write(client, skb->data, skb->len);
>
> Here, we would have:
>
> 	r = pn544_hci_i2c_write(client, skb->data, skb->len);
> 	pn544_hci_remove_len_crc(skb);
> 	return r;
>
>>>   	info->shdlc = nfc_shdlc_allocate(&pn544_shdlc_ops,
>>>   					 &init_data, protocols,
>>> -					 PN544_CMDS_HEADROOM, 0,
>>> +					 PN544_CMDS_HEADROOM, PN544_CMDS_TAILROOM,
>>>   					 PN544_HCI_LLC_MAX_PAYLOAD,
>>>   					 dev_name(&client->dev));
>
> And this should be:
>
>    	info->shdlc = nfc_shdlc_allocate(&pn544_shdlc_ops,
>    					 &init_data, protocols,
>   					 PN544_CMDS_HEADROOM +
> 					 PN544_FRAME_HEADROOM,
> 					 PN544_FRAME_TAILROOM,
>    					 PN544_HCI_LLC_MAX_PAYLOAD,
>    					 dev_name(&client->dev));
>
> note that PN544_CMDS_HEADROOM is really only for skb allocated by HCI
> (or NFC Core), not by those allocated by shdlc, but we aggregate it all
> in a single parameter for simplicity.

Now, I see the point. Will update the patch.

Thanks,
/Waldek