igc: read before write to SRRCTL register

[ Upstream commit 3ce29c17dc847bf4245e16aad78a7617afa96297 ]

igc_configure_rx_ring() function will be called as part of XDP program
setup. If Rx hardware timestamp is enabled prio to XDP program setup,
this timestamp enablement will be overwritten when buffer size is
written into SRRCTL register.

Thus, this commit read the register value before write to SRRCTL
register. This commit is tested by using xdp_hw_metadata bpf selftest
tool. The tool enables Rx hardware timestamp and then attach XDP program
to igc driver. It will display hardware timestamp of UDP packet with
port number 9092. Below are detail of test steps and results.

Command on DUT:
  sudo ./xdp_hw_metadata <interface name>

Command on Link Partner:
  echo -n skb | nc -u -q1 <destination IPv4 addr> 9092

Result before this patch:
  skb hwtstamp is not found!

Result after this patch:
  found skb hwtstamp = 1677800973.642836757

Optionally, read PHC to confirm the values obtained are almost the same:
Command:
  sudo ./testptp -d /dev/ptp0 -g
Result:
  clock time: 1677800973.913598978 or Fri Mar  3 07:49:33 2023

Fixes: fc9df2a0b520 ("igc: Enable RX via AF_XDP zero-copy")
Cc: <stable@vger.kernel.org> # 5.14+
Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jesper Dangaard Brouer <brouer@redhat.com>
Tested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/intel/igc/igc_base.h b/drivers/net/ethernet/intel/igc/igc_base.h
index ce530f5fd7bdad08663a9e766c02f163f309dcf4..52849f5e8048d4b4558598f86e5551273cccaa46 100644 (file)
--- a/drivers/net/ethernet/intel/igc/igc_base.h
+++ b/drivers/net/ethernet/intel/igc/igc_base.h
@@ -85,8 +85,13 @@ union igc_adv_rx_desc {
 #define IGC_RXDCTL_SWFLUSH             0x04000000 /* Receive Software Flush */
 
 /* SRRCTL bit definitions */
-#define IGC_SRRCTL_BSIZEPKT_SHIFT              10 /* Shift _right_ */
-#define IGC_SRRCTL_BSIZEHDRSIZE_SHIFT          2  /* Shift _left_ */
-#define IGC_SRRCTL_DESCTYPE_ADV_ONEBUF 0x02000000
+#define IGC_SRRCTL_BSIZEPKT_MASK       GENMASK(6, 0)
+#define IGC_SRRCTL_BSIZEPKT(x)         FIELD_PREP(IGC_SRRCTL_BSIZEPKT_MASK, \
+                                       (x) / 1024) /* in 1 KB resolution */
+#define IGC_SRRCTL_BSIZEHDR_MASK       GENMASK(13, 8)
+#define IGC_SRRCTL_BSIZEHDR(x)         FIELD_PREP(IGC_SRRCTL_BSIZEHDR_MASK, \
+                                       (x) / 64) /* in 64 bytes resolution */
+#define IGC_SRRCTL_DESCTYPE_MASK       GENMASK(27, 25)
+#define IGC_SRRCTL_DESCTYPE_ADV_ONEBUF FIELD_PREP(IGC_SRRCTL_DESCTYPE_MASK, 1)
 
 #endif /* _IGC_BASE_H */

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index a47dce10d3a78cd0276ef0c164af01aef9f87490..a8c24a1c12b434a0e0dfca71139dbe00dd0acae0 100644 (file)
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -674,8 +674,11 @@ static void igc_configure_rx_ring(struct igc_adapter *adapter,
        else
                buf_size = IGC_RXBUFFER_2048;
 
-       srrctl = IGC_RX_HDR_LEN << IGC_SRRCTL_BSIZEHDRSIZE_SHIFT;
-       srrctl |= buf_size >> IGC_SRRCTL_BSIZEPKT_SHIFT;
+       srrctl = rd32(IGC_SRRCTL(reg_idx));
+       srrctl &= ~(IGC_SRRCTL_BSIZEPKT_MASK | IGC_SRRCTL_BSIZEHDR_MASK |
+                   IGC_SRRCTL_DESCTYPE_MASK);
+       srrctl |= IGC_SRRCTL_BSIZEHDR(IGC_RX_HDR_LEN);
+       srrctl |= IGC_SRRCTL_BSIZEPKT(buf_size);
        srrctl |= IGC_SRRCTL_DESCTYPE_ADV_ONEBUF;
 
        wr32(IGC_SRRCTL(reg_idx), srrctl);