On Thu, Nov 27, 2014 at 05:55:43AM +0000, bpqw wrote: > >What's the difference between using EVCR and the ENTER QUAD I/O MODE > >(35h) command I see in some of your datasheets? Are both supported on all > >Micron quad I/O SPI NOR flash? > > There is no difference between using EVCR and the ENTER QUAD I/O MODE command. > But, for some Micron spi nor, there no ENTER Quad I/O command(35h),such as > n25q064. > for all current Micron spi nor, if it support quad I/O mode, Using EVCR > definitely be supported. > So, we recommend that enable QUAD I/O mode by writing ECVR.
Good to know. Thanks for the info. Maybe you can note this somewhere in your next version, like a comment in the commit description. > >Also, which SPI NOR is this enabled for? I don't see any Micron entries in > >spi_nor_ids[] which contain the SPI_NOR_QUAD_READ flag. > > Yes, we now don't see any Micron entries in spi_nor_ids[] which > contain the SPI_NOR_QUAD_READ flag. But Micron spi nor in > spi_nor_ids[] all support Quad I/O mode. Then add them! At least, for flash that support them (for all packages that might share the same ID). > maybe customer want to use default mode(extended I/O mode), > When submitted relevant patch, they didn't SPI_NOR_QUAD_READ flag in the > spi_nor_ids[]. The flag may have been omitted because it didn't exist at the time. Or it didn't get tested. Regardless, just because you enable this flag in spi_nor_ids[] doesn't mean that it will enable Quad I/O for users that can't support it; board files / DT descriptions still have to opt in by advertising hardware support for Quad I/O. See, for example, spi-tx-bus-width and spi-rx-bus-width properties in Documentation/devicetree/bindings/spi/spi-bus.txt. > This patch is just for wanting to enable Micron Quad I/O mode. That's fine. But I'd welcome any follow-up patch to add the QUAD flag to the right Micron table entries. Otherwise, this patch doesn't actually help anyone. BTW, given that you aren't changing any entries to spi_nor_ids[] yet, have you actually tested this patch? Or are you only working off the specifications / datasheets? Thanks, Brian -- 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/
