6.14-stable review patch. If anyone has any objections, please let me know.
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From: Raju Rangoju Raju.Rangoju@amd.com
[ Upstream commit 8e4d3d8a5e51e07bd0d6cdd81b5e4af79f796927 ]
For some SPI flash memory operations, dummy bytes are not mandatory. For example, in Winbond SPINAND flash memory devices, the `write_cache` and `update_cache` operation variants have zero dummy bytes. Calculating the duration for SPI memory operations with zero dummy bytes causes a divide error when `ncycles` is calculated in the spi_mem_calc_op_duration().
Add changes to skip the 'ncylcles' calculation for zero dummy bytes.
Following divide error is fixed by this change:
Oops: divide error: 0000 [#1] PREEMPT SMP NOPTI ...
? do_trap+0xdb/0x100 ? do_error_trap+0x75/0xb0 ? spi_mem_calc_op_duration+0x56/0xb0 ? exc_divide_error+0x3b/0x70 ? spi_mem_calc_op_duration+0x56/0xb0 ? asm_exc_divide_error+0x1b/0x20 ? spi_mem_calc_op_duration+0x56/0xb0 ? spinand_select_op_variant+0xee/0x190 [spinand] spinand_match_and_init+0x13e/0x1a0 [spinand] spinand_manufacturer_match+0x6e/0xa0 [spinand] spinand_probe+0x357/0x7f0 [spinand] ? kernfs_activate+0x87/0xd0 spi_mem_probe+0x7a/0xb0 spi_probe+0x7d/0x130
Fixes: 226d6cb3cb79 ("spi: spi-mem: Estimate the time taken by operations") Suggested-by: Krishnamoorthi M krishnamoorthi.m@amd.com Co-developed-by: Akshata MukundShetty akshata.mukundshetty@amd.com Signed-off-by: Akshata MukundShetty akshata.mukundshetty@amd.com Signed-off-by: Raju Rangoju Raju.Rangoju@amd.com Link: https://patch.msgid.link/20250424121333.417372-1-Raju.Rangoju@amd.com Reviewed-by: Miquel Raynal miquel.raynal@bootlin.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/spi/spi-mem.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c index a9f0f47f4759b..74b013c41601d 100644 --- a/drivers/spi/spi-mem.c +++ b/drivers/spi/spi-mem.c @@ -585,7 +585,11 @@ u64 spi_mem_calc_op_duration(struct spi_mem_op *op) ns_per_cycles = 1000000000 / op->max_freq; ncycles += ((op->cmd.nbytes * 8) / op->cmd.buswidth) / (op->cmd.dtr ? 2 : 1); ncycles += ((op->addr.nbytes * 8) / op->addr.buswidth) / (op->addr.dtr ? 2 : 1); - ncycles += ((op->dummy.nbytes * 8) / op->dummy.buswidth) / (op->dummy.dtr ? 2 : 1); + + /* Dummy bytes are optional for some SPI flash memory operations */ + if (op->dummy.nbytes) + ncycles += ((op->dummy.nbytes * 8) / op->dummy.buswidth) / (op->dummy.dtr ? 2 : 1); + ncycles += ((op->data.nbytes * 8) / op->data.buswidth) / (op->data.dtr ? 2 : 1);
return ncycles * ns_per_cycles;