[Qemu-devel] [PATCH v1] xilinx_spips dummy bytes fix

[Qemu-devel] [PATCH v1] xilinx_spips dummy bytes fix

[Sai Pavan Boddu]

For zynq-7000 boards, we saw issues when u-boot/linux accessing the qspi.
Issue is due to wrong dummy byte transfers for few of un-handled commands ex: 0x9F, 0x6, 0xe9, 0x4, 0x18, etc
There are many unhandled commands which do not require dummy bytes but they can be followed by address cycles.

To fix this issue for above commands, the next upcoming tx bytes are not considered dummies rather sent to slave directly.

Sai Pavan Boddu (1):
  xilinx_spips: send dummy only if cmd requires it

 hw/ssi/xilinx_spips.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

-- 
2.7.4

[Qemu-devel] [PATCH v1] xilinx_spips: send dummy only if cmd requires it

[Sai Pavan Boddu]

For all the commands, which do not have an entry in
xilinx_spips_num_dummies, present logic sends dummy byte when ever we
are in SNOOP_NONE state, fix it to send only if cmd requires them.

Only transmit max of 1 dummy byte(i.e 8 cycles) is a single snoop cycle.
And also convert dummy bytes to cycles (required by m25p80).

Signed-off-by: Sai Pavan Boddu <saipava@xilinx.com>
---
 hw/ssi/xilinx_spips.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/hw/ssi/xilinx_spips.c b/hw/ssi/xilinx_spips.c
index 426f971..8278930 100644
--- a/hw/ssi/xilinx_spips.c
+++ b/hw/ssi/xilinx_spips.c
@@ -627,10 +627,17 @@ static void xilinx_spips_flush_txfifo(XilinxSPIPS *s)
                 tx_rx[i] = tx;
             }
         } else {
-            /* Extract a dummy byte and generate dummy cycles according to the
-             * link state */
             tx = fifo8_pop(&s->tx_fifo);
-            dummy_cycles = 8 / s->link_state;
+            if (s->cmd_dummies > 0) {
+                /* Extract a dummy byte and generate dummy cycles according to
+                 * the link state */
+                 dummy_cycles = (s->cmd_dummies ? 1 : 0) * 8 / s->link_state;
+                 s->cmd_dummies--;
+            } else {
+                for (i = 0; i < num_effective_busses(s); ++i) {
+                    tx_rx[i] = tx;
+                }
+            }
         }
 
         for (i = 0; i < num_effective_busses(s); ++i) {
-- 
2.7.4