Hi Cyrille, Marek, Thanks for your suggestions. On Thu, 2017-03-30 at 19:40 +0200, Cyrille Pitchen wrote: > Hi Guochun, > > Le 30/03/2017 à 10:23, Guochun Mao a écrit : > > when nor's size larger than 16MByte, nor and controller should > > enter 4Byte mode simultaneously. > > > > Signed-off-by: Guochun Mao <guochun.mao@xxxxxxxxxxxx> > > --- > > drivers/mtd/spi-nor/mtk-quadspi.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/drivers/mtd/spi-nor/mtk-quadspi.c b/drivers/mtd/spi-nor/mtk-quadspi.c > > index e661877..05cd8a8 100644 > > --- a/drivers/mtd/spi-nor/mtk-quadspi.c > > +++ b/drivers/mtd/spi-nor/mtk-quadspi.c > > @@ -369,6 +369,13 @@ static int mt8173_nor_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, > > /* We only handle 1 byte */ > > ret = mt8173_nor_wr_sr(mt8173_nor, *buf); > > break; > > + case SPINOR_OP_EN4B: > > + /* Set nor controller to 4-byte address mode, > > + * and simultaneously set nor flash. > > + * This case should cooperate with default operation. > > + */ > > + writeb(readb(mt8173_nor->base + MTK_NOR_DUAL_REG) | 0x10, > > + mt8173_nor->base + MTK_NOR_DUAL_REG); > > This is not good: you should check in both mt8173_nor_read() and > mt8173_nor_write() whether nor->addr_width is either 3 or 4. > > from include/linux/mtd/spi-nor.h: > * @addr_width: number of address bytes > > Besides SPI commands using an op code from 4-byte address instruction > set always carry a 4-byte address. They can be used directly, without > sending the SPINOR_OP_EN4B before. So you cannot assume that addresses > will be 4-byte long only if your SPI controller driver has seen a > SPINOR_OP_EN4B command before. This assumption is wrong. Nor->addr_width is assigned in spi_nor_scan in spi-nor.c, and it's not modified in later process. Does it means that we will not switch nor between 3Byte address and 4Byte? So, is it better to check nor->addr_width when do nor initialization? > > SPI controller driver should never check SPINOR_OP_* op codes like this. I agree that SPI controller driver should not check SPINOR_OP_* op codes like what I do. I will correct it next version. Best Regards, Guochun > > Then, testing SPINOR_OP_RDSR from mt8173_nor_read_reg() or > SPINOR_OP_WRSR from mt8173_nor_write_reg() is not a good practice too: > op codes may change depending on the memory manufacturer. So testing op > code values like you do can work with some memories but maybe not all. > > Finally, don't use 0x10, please define a macro instead. > > Best regards, > > Cyrille > > > default: > > ret = mt8173_nor_do_tx_rx(mt8173_nor, opcode, buf, len, NULL, 0); > > if (ret) > > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
