On 01-07-15 04:19, Bean Huo 霍斌斌 (beanhuo) wrote: >> drivers/mtd/spi-nor/spi-nor.c | 2 ++ >> 1 file changed, 2 insertions(+) > >> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c >> index e8f6131..10ba94f 100644 >> --- a/drivers/mtd/spi-nor/spi-nor.c >> +++ b/drivers/mtd/spi-nor/spi-nor.c >> @@ -1398,6 +1398,8 @@ static int set_quad_mode(struct spi_nor *nor, struct >> flash_info *info) > > } > > return status; > > case CFI_MFR_ST: >> + if (!(nor->spi->mode & SPI_TX_QUAD)) >> + return 0; > I think, this action should be done before callback set_quad_mode,and add > some codes in > Spi controller driver.what is more,how do you get spi member in spi_nor?seems > no this member.
Too many changes between the Xilinx tree and mainline. My patch isn't for mainline, I'll make a new one. > I have one concern that as long as spi nor be configed into quad mode,spi > controller must be also > immediately Transfer into quad mode, otherwise read status will be fail. The original commit that added the micron Quad mode did not do this. I wonder how this was tested, because it could never have worked on any setup I'm aware of. After setting the "quad mode" bit in volatile config, the controller needs to start sending commands on all 4 lanes. Even if it succeeds in doing that, a soft reset (e.g. unloading/loading the driver, or kexec to another kernel) will bring the system in a state where the controller will use 1 lane for commands while the chip expects 4, thus breaking all communication. Having slept and pondered about this, I suggest plainly removing the Micron Quad mode code, because it is just broken and can never work. There's no actual performance advantage here, apart from just saving a few clocks on commands, which would be less than 0.1% on a 1k data read. > But setting spi controller layer(driver/spi/) and configure spi nor > layer(driver/mtd/spi-nor) > are not the same mtd layer,I found that it's hard to do. > But for new structure spi controller(such as > driver/mtd/spi-nor/fsl-quadspi.c) is very reasonable.and > it can be easy to set spi controller and spi nor into quad mode at the same > time. I'm sorry, but I didn't understand what you meant here. Kind regards, Mike Looijmans System Expert TOPIC Embedded Products Eindhovenseweg 32-C, NL-5683 KH Best Postbus 440, NL-5680 AK Best Telefoon: +31 (0) 499 33 69 79 Telefax: +31 (0) 499 33 69 70 E-mail: mike.looijm...@topicproducts.com Website: www.topicproducts.com Please consider the environment before printing this e-mail -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
