stmmac: add descriptors function for GMAC 4.xx

Hello Alexandre TORGUE,

The patch 753a71090f33: "stmmac: add descriptors function for GMAC 4.xx" from Apr 1, 2016, leads to the following static checker warning:

	drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c:261 dwmac4_rd_prepare_tx_desc()
	warn: odd binop '0x4000 & 0x3fff'

drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c
251 static void dwmac4_rd_prepare_tx_desc(struct dma_desc *p, int is_fs, int len,
252 bool csum_flag, int mode, bool tx_own,
253 bool ls)
254 {
255 unsigned int tdes3 = p->des3;
256
257 if (unlikely(len > BUF_SIZE_16KiB)) {
258 p->des2 |= (((len - BUF_SIZE_16KiB) <<
259 TDES2_BUFFER2_SIZE_MASK_SHIFT)
260 & TDES2_BUFFER2_SIZE_MASK)

   261                              | (BUF_SIZE_16KiB & TDES2_BUFFER1_SIZE_MASK);
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Should this be "len & TDES2_BUFFER1_SIZE_MASK" or are you rounding down the length deliberately?

   262          } else {
   263                  p->des2 |= (len & TDES2_BUFFER1_SIZE_MASK);
   264          }
   265  
   266          if (is_fs)
   267                  tdes3 |= TDES3_FIRST_DESCRIPTOR;
   268          else
   269                  tdes3 &= ~TDES3_FIRST_DESCRIPTOR;
   270  

regards,
dan carpenter

Hello Dan,

It is a mistake. Could be "len & TDES2_BUFFER1_SIZE_MASK" or "(BUF_SIZE_16KiB - 1) & TDES2_BUFFER1_SIZE_MASK". I will send a fix.

Thanks.

regards,

Alex