Re: [PATCH net 3/4] Revert "sh_eth: Enable Rx descriptor word 0 shift for r8a7790"
From: Sergei Shtylyov <hidden>
Date: 2015-02-26 19:18:01
Hello. On 02/26/2015 05:21 PM, Ben Hutchings wrote:
This reverts commit fd9af07c3404ac9ecbd0d859563360f51ce1ffde.
The hardware manual states that the frame error and multicast bits are copied to bits 9:0 of RD0, not bits 25:16. I've tested that this is true for RFS1 (CRC error), RFS3 (frame too short), RFS4 (frame too long) and RFS8 (multicast).
Well, if your testing does match the manual, the reverted patch was most
probably just wrong in the first place.
Signed-off-by: Ben Hutchings <redacted> --- drivers/net/ethernet/renesas/sh_eth.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
quoted hunk ↗ jump to hunk
diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c index ed67951f5271..317722e16043 100644 --- a/drivers/net/ethernet/renesas/sh_eth.c +++ b/drivers/net/ethernet/renesas/sh_eth.c
[...]
quoted hunk ↗ jump to hunk
@@ -1459,8 +1458,8 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota) /* In case of almost all GETHER/ETHERs, the Receive Frame State * (RFS) bits in the Receive Descriptor 0 are from bit 9 to - * bit 0. However, in case of the R8A7740, R8A779x, and - * R7S72100 the RFS bits are from bit 25 to bit 16. So, the + * bit 0. However, in case of the R8A7740 and R7S72100 + * the RFS bits are from bit 25 to bit 16. So, the
And that seems more logical to me, as we have the RFS bits starting with
bit 16 only on the SoCs with the GEther compatible register layout (though the
latter SoC doesn't support Gigabit speed).
Having the RFS bits start at bit 16 is most probably connected to a SoC
having support for hardware checksumming (bit 0-15 store the received frame
checksum for at least R7S72100), so merging the 'shift_rd0' and 'hw_crc' flags
seemed the reasonable next step to me (not taken due to the lack of
documentation)...
* driver needs right shifting by 16. */ if (mdp->cd->shift_rd0)
This hunk (inverted) was not a part of the commit you're reverting.
Perhaps you shouldn't call this patch revert? Or make a remark about this hunk
in the change-log?
WBR, Sergei