Re: [U-Boot] [PATCH v2 38/40] net: rtl8169: Properly align buffers

13 Nov 2014

Hi,
I tested on sh7785lcr board with this patch.
This worked without any problems. Thanks.
2014-08-27 0:34 GMT+09:00 Thierry Reding thierry.reding@gmail.com:
...
From: Thierry Reding treding@nvidia.com
RX and TX descriptor rings should be aligned to 256 byte boundaries. Use
the DEFINE_ALIGN_BUFFER() macro to define the buffers so that they don't
have to be manually aligned later on. Also make sure that the buffers do
align to cache-line boundaries in case the cache-line is higher than the
256 byte alignment requirements of the NIC.
Also add a warning if the cache-line size is larger than the descriptor
size, because the driver may discard changes to descriptors made by the
hardware when requeuing RX buffers.
Signed-off-by: Thierry Reding treding@nvidia.com
Changes in v2:

make cache-line vs. descriptor size a compile-time warning

Tested-by: Nobuhiro Iwamatsu nobuhiro.iwamatsu.yj@renesas.com
...
drivers/net/rtl8169.c | 63 +++++++++++++++++++++++++++------------------------
 1 file changed, 34 insertions(+), 29 deletions(-)

diff --git a/drivers/net/rtl8169.c b/drivers/net/rtl8169.c
index c3eb474f0fba..d81ee8af1cc1 100644
--- a/drivers/net/rtl8169.c
+++ b/drivers/net/rtl8169.c
@@ -277,23 +277,41 @@ struct RxDesc {
        u32 buf_Haddr;
 };
-/* Define the TX Descriptor */
-static u8 tx_ring[NUM_TX_DESC * sizeof(struct TxDesc) + 256];
-/*     __attribute__ ((aligned(256))); */
+#define RTL8169_DESC_SIZE 16
-/* Create a static buffer of size RX_BUF_SZ for each
-TX Descriptor. All descriptors point to a
-part of this buffer */
-static unsigned char txb[NUM_TX_DESC * RX_BUF_SIZE];
+#if ARCH_DMA_MINALIGN > 256
+#  define RTL8169_ALIGN ARCH_DMA_MINALIGN
+#else
+#  define RTL8169_ALIGN 256
+#endif



+/*


Warn if the cache-line size is larger than the descriptor size. In such



cases the driver will likely fail because the CPU needs to flush the cache



when requeuing RX buffers, therefore descriptors written by the hardware



may be discarded.


*/

+#if RTL8169_DESC_SIZE < ARCH_DMA_MINALIGN
+#warning cache-line size is larger than descriptor size
+#endif



+/* Define the TX Descriptor */
+DEFINE_ALIGN_BUFFER(struct TxDesc, tx_ring, NUM_TX_DESC, RTL8169_ALIGN);
/* Define the RX Descriptor */
-static u8 rx_ring[NUM_RX_DESC * sizeof(struct TxDesc) + 256];

/*  __attribute__ ((aligned(256))); */

+DEFINE_ALIGN_BUFFER(struct RxDesc, rx_ring, NUM_RX_DESC, RTL8169_ALIGN);
-/* Create a static buffer of size RX_BUF_SZ for each
-RX Descriptor  All descriptors point to a
-part of this buffer */
-static unsigned char rxb[NUM_RX_DESC * RX_BUF_SIZE];
+/*


Create a static buffer of size RX_BUF_SZ for each TX Descriptor. All



descriptors point to a part of this buffer.


*/

+DEFINE_ALIGN_BUFFER(u8, txb, NUM_TX_DESC * RX_BUF_SIZE, RTL8169_ALIGN);



+/*


Create a static buffer of size RX_BUF_SZ for each RX Descriptor. All



descriptors point to a part of this buffer.


*/

+DEFINE_ALIGN_BUFFER(u8, rxb, NUM_RX_DESC * RX_BUF_SIZE, RTL8169_ALIGN);
struct rtl8169_private {
        void *mmio_addr;        /* memory map physical address */
@@ -301,8 +319,6 @@ struct rtl8169_private {
        unsigned long cur_rx;   /* Index into the Rx descriptor buffer of next Rx pkt. */
        unsigned long cur_tx;   /* Index into the Tx descriptor buffer of next Rx pkt. */
        unsigned long dirty_tx;

  unsigned char *TxDescArrays;    /* Index of Tx Descriptor buffer */


  unsigned char *RxDescArrays;    /* Index of Rx Descriptor buffer */
  struct TxDesc *TxDescArray;     /* Index of 256-alignment Tx Descriptor buffer */
  struct RxDesc *RxDescArray;     /* Index of 256-alignment Rx Descriptor buffer */
  unsigned char *RxBufferRings;   /* Index of Rx Buffer  */



@@ -710,16 +726,6 @@ static int rtl_reset(struct eth_device *dev, bd_t *bis)
        printf ("%s\n", __FUNCTION__);
 #endif

  tpc->TxDescArrays = tx_ring;


  /* Tx Desscriptor needs 256 bytes alignment; */


  tpc->TxDescArray = (struct TxDesc *) ((unsigned long)(tpc->TxDescArrays +


                                                        255) & ~255);



  tpc->RxDescArrays = rx_ring;


  /* Rx Desscriptor needs 256 bytes alignment; */


  tpc->RxDescArray = (struct RxDesc *) ((unsigned long)(tpc->RxDescArrays +


                                                        255) & ~255);


  rtl8169_init_ring(dev);
  rtl8169_hw_start(dev);
  /* Construct a perfect filter frame with the mac address as first match



@@ -761,10 +767,6 @@ static void rtl_halt(struct eth_device *dev)
    RTL_W32(RxMissed, 0);



  tpc->TxDescArrays = NULL;


  tpc->RxDescArrays = NULL;


  tpc->TxDescArray = NULL;


  tpc->RxDescArray = NULL;
  for (i = 0; i < NUM_RX_DESC; i++) {
          tpc->RxBufferRing[i] = NULL;
  }



@@ -909,6 +911,9 @@ static int rtl_init(struct eth_device *dev, bd_t *bis)
 #endif
        }

  tpc->TxDescArray = tx_ring;


  tpc->RxDescArray = rx_ring;


  return 1;



}
--
2.0.4

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-- 
Nobuhiro Iwamatsu

    