On 11/29/09 00:55, Benoit PAPILLAULT wrote:
> Gertjan van Wingerde a écrit :
>> On 11/28/09 22:26, Ivo van Doorn wrote:
>>>> diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.c b/drivers/net/wireless/rt2x00/rt2x00queue.c
>>>> index b8f0954..562a344 100644
>>>> --- a/drivers/net/wireless/rt2x00/rt2x00queue.c
>>>> +++ b/drivers/net/wireless/rt2x00/rt2x00queue.c
>>>> @@ -181,7 +181,7 @@ void rt2x00queue_insert_l2pad(struct sk_buff *skb, unsigned int header_length)
>>>> unsigned int frame_length = skb->len;
>>>> unsigned int header_align = ALIGN_SIZE(skb, 0);
>>>> unsigned int payload_align = ALIGN_SIZE(skb, header_length);
>>>> - unsigned int l2pad = 4 - (payload_align - header_align);
>>>> + unsigned int l2pad = 4 - (header_length & 3);
>
> Humm... is header_length = 24, then your formula gives l2pad = 4. If so,
> this is wrong. Do I miss something?
No, you are right. The formula needs another & 3 on the overall result to account for that situation.
So, it should be:
unsigned int l2pad = (4 - (header_length & 3)) & 3;
>
> BTW, I'm trying to prepare some patches for rt2800usb and padding. I
> must admit the current framework is a bit complex compared to other
> drivers (ath9k for instance).
>
> To give something similar to ath9k where the pad position is computed
> based on the hdr->frame_control field only (my guess is that's what the
> HW does anyway), we have :
>
> int rt2800usb_padpos(__le16 frame_control)
> {
> int padpos = 24;
> if (ieee80211_is_data(frame_control)) {
> padpos = ieee80211_hdrlen(frame_control);
> }
> return padpos;
> }
>
> then later : int padsize = padpos & 3;
>
> then the usual check before doing the real padding or unpadding :
> if (padsize && skb->len>padpos) {
> do padding or unpadding
> }
>
To be honest, I don't think padding sizes depend the type of frame. It is just a matter of the
header_length. So, I don't think we have to complicate this by looking at the type of frame.
---
Gertjan.
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