[PATCH 4.4 10/63] spi: xilinx: Detect stall with Unknown commands

Greg Kroah-Hartman
2018-01-01T14:25:32Z

From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>

commit 5a1314fa697fc65cefaba64cd4699bfc3e6882a6 upstream.

When the core is configured in C_SPI_MODE > 0, it integrates a
lookup table that automatically configures the core in dual or quad mode
based on the command (first byte on the tx fifo).

Unfortunately, that list mode_?_memoy_*.mif does not contain all the
supported commands by the flash.

Since 4.14 spi-nor automatically tries to probe the flash using SFDP
(command 0x5a), and that command is not part of the list_mode table.

Whit the right combination of C_SPI_MODE and C_SPI_MEMORY this leads
into a stall that can only be recovered with a soft rest.

This patch detects this kind of stall and returns -EIO to the caller on
those commands. spi-nor can handle this error properly:

m25p80 spi0.0: Detected stall. Check C_SPI_MODE and C_SPI_MEMORY. 0x21 0x2404
m25p80 spi0.0: SPI transfer failed: -5
spi_master spi0: failed to transfer one message from queue
m25p80 spi0.0: s25sl064p (8192 Kbytes)

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/spi/spi-xilinx.c | 11 +++++++++++
1 file changed, 11 insertions(+)

--- a/drivers/spi/spi-xilinx.c
+++ b/drivers/spi/spi-xilinx.c
@@ -271,6 +271,7 @@ static int xilinx_spi_txrx_bufs(struct s
while (remaining_words) {
int n_words, tx_words, rx_words;
u32 sr;
+ int stalled;

n_words = min(remaining_words, xspi->buffer_size);

@@ -299,7 +300,17 @@ static int xilinx_spi_txrx_bufs(struct s

/* Read out all the data from the Rx FIFO */
rx_words = n_words;
+ stalled = 10;
while (rx_words) {
+ if (rx_words == n_words && !(stalled--) &&
+ !(sr & XSPI_SR_TX_EMPTY_MASK) &&
+ (sr & XSPI_SR_RX_EMPTY_MASK)) {
+ dev_err(&spi->dev,
+ "Detected stall. Check C_SPI_MODE and C_SPI_MEMORY\n");
+ xspi_init_hw(xspi);
+ return -EIO;
+ }
+
if ((sr & XSPI_SR_TX_EMPTY_MASK) && (rx_words > 1)) {
xilinx_spi_rx(xspi);
rx_words--;