Unverified Commit 4cafadde authored by Chuanhong Guo's avatar Chuanhong Guo Committed by Mark Brown
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spi: spi-mtk-nor: fix timeout calculation overflow 



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:
1. calculate clock / 1000000 first
2. add a 4M transfer size cap so that the final timeout in DMA reading
   doesn't overflow

Fixes: 881d1ee9 ("spi: add support for mediatek spi-nor controller")
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarChuanhong Guo <gch981213@gmail.com>
Link: https://lore.kernel.org/r/20200922114905.2942859-1-gch981213@gmail.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent f09a433b

drivers/spi/spi-mtk-nor.c

+5 −1
Original line number Diff line number Diff line
@@ -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 overflow

			if (op->data.nbytes > 0x400000)

				op->data.nbytes = 0x400000;



			if ((op->addr.val & MTK_NOR_DMA_ALIGN_MASK) ||

			    (op->data.nbytes < MTK_NOR_DMA_ALIGN))

				op->data.nbytes = 1;