On Tue, Sep 22, 2020 at 7:43 PM Chuanhong Guo gch981213@gmail.com wrote:
CLK_TO_US macro is used to calculate potential transfer time for various timeout handling. However it overflows on transfer bigger than 512 bytes because it first did (len * 8 * 1000000). This controller typically operates at 45MHz. This patch did 2 things:
- calculate clock / 1000000 first
- add a 4M transfer size cap so that the final timeout in DMA reading doesn't overflow
Fixes: 881d1ee9fe81f ("spi: add support for mediatek spi-nor controller") Cc: stable@vger.kernel.org Signed-off-by: Chuanhong Guo gch981213@gmail.com
drivers/spi/spi-mtk-nor.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c index 6e6ca2b8e6c82..619313db42c0e 100644 --- a/drivers/spi/spi-mtk-nor.c +++ b/drivers/spi/spi-mtk-nor.c @@ -89,7 +89,7 @@ // Buffered page program can do one 128-byte transfer #define MTK_NOR_PP_SIZE 128
-#define CLK_TO_US(sp, clkcnt) ((clkcnt) * 1000000 / sp->spi_freq) +#define CLK_TO_US(sp, clkcnt) DIV_ROUND_UP(clkcnt, sp->spi_freq / 1000000)
struct mtk_nor { struct spi_controller *ctlr; @@ -177,6 +177,10 @@ static int mtk_nor_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op) if ((op->addr.nbytes == 3) || (op->addr.nbytes == 4)) { if ((op->data.dir == SPI_MEM_DATA_IN) && mtk_nor_match_read(op)) {
// limit size to prevent timeout calculation overflowif (op->data.nbytes > 0x2000000)op->data.nbytes = 0x2000000;
Sorry, wrong patch. This cap should be 4M not 32M. I'll send a v2 immediately.