Hi Wolfram,
May I please ask you with an ks7010 driver endianness question?
Comments on the hostif_hdr data structure (ks_hostif.h) state that the
target uses little endian byte order.
/*
* HOST-MAC I/F data structure
* Byte alignmet Little Endian
*/
struct hostif_hdr {
u16 size;
u16 event;
} __packed;
On the rx data path this header is unpacked using get_WORD()
void hostif_receive(struct ks_wlan_private *priv, unsigned char *p,
unsigned int size)
{
DPRINTK(4, "\n");
devio_rec_ind(priv, p, size);
priv->rxp = p;
priv->rx_size = size;
if (get_WORD(priv) == priv->rx_size) { /* length check !! */
hostif_event_check(priv); /* event check */
}
}
get_WORD() inverts the byte order
static inline u16 get_WORD(struct ks_wlan_private *priv)
{
u16 data;
data = (get_BYTE(priv) & 0xff);
data |= ((get_BYTE(priv) << 8) & 0xff00);
return data;
}
Am I missing something? It seems that this code will only work if the
host and the target have differing endianness. It seems unlikely that
the driver was tested solely on a big-endian machine, is the comment
wrong - is the target actually big-endian?
Off topic, I watched your 2014 Fosdem talk on adding device support to
the kernel without adding code. It was very educational.
thanks for your time,
Tobin.
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