Re: [PATCH] spi: zynqmp_gqspi: Fix write issue at low frequencies

[Michal Simek]

On 10/19/21 16:13, Ashok Reddy Soma wrote:

With current implementation we are seeing write issues at low frequencies
below 15Mhz. Make below changes to fix the issue.

1. Remove dummy genfifo entry in zynqmp_qspi_chipselect() which was
    incorrectly added in the past

2. Enable and poll for TX_FIFO_Empty after Tx data is filled in FIFO in
    zynqmp_qspi_fill_tx_fifo().

Signed-off-by: Ashok Reddy Soma <ashok.reddy.s...@xilinx.com>
---

  drivers/spi/zynqmp_gqspi.c | 11 ++++++++---
  1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/zynqmp_gqspi.c b/drivers/spi/zynqmp_gqspi.c
index 2db4ae20f1..c772bae3cc 100644
--- a/drivers/spi/zynqmp_gqspi.c
+++ b/drivers/spi/zynqmp_gqspi.c
@@ -37,6 +37,7 @@
   */
  #define GQSPI_IXR_TXNFULL_MASK                0x00000004 /* QSPI TX FIFO 
Overflow */
  #define GQSPI_IXR_TXFULL_MASK         0x00000008 /* QSPI TX FIFO is full */
+#define GQSPI_IXR_TXFIFOEMPTY_MASK     0x00000100 /* QSPI TX FIFO is Empty */
  #define GQSPI_IXR_RXNEMTY_MASK                0x00000010 /* QSPI RX FIFO Not 
Empty */
  #define GQSPI_IXR_GFEMTY_MASK         0x00000080 /* QSPI Generic FIFO Empty */
  #define GQSPI_IXR_GFNFULL_MASK                0x00000200 /* QSPI GENFIFO not 
full */
@@ -279,9 +280,6 @@ static void zynqmp_qspi_chipselect(struct zynqmp_qspi_priv 
*priv, int is_on)

debug("GFIFO_CMD_CS: 0x%x\n", gqspi_fifo_reg); - /* Dummy generic FIFO entry */

-       zynqmp_qspi_fill_gen_fifo(priv, 0);
-
        zynqmp_qspi_fill_gen_fifo(priv, gqspi_fifo_reg);
  }

@@ -470,6 +468,13 @@ static int zynqmp_qspi_fill_tx_fifo(struct zynqmp_qspi_priv *priv, u32 size)

                }
        }

+ ret = wait_for_bit_le32(&regs->isr, GQSPI_IXR_TXFIFOEMPTY_MASK, 1,

+                               GQSPI_TIMEOUT, 1);
+       if (ret) {
+               printf("%s: Timeout\n", __func__);
+               return ret;
+       }
+
        priv->tx_buf += len;
        return 0;
  }

applied.
M