* Gupta, Pekon <pekon@xxxxxx> [140519 23:10]: > From: Tony Lindgren [mailto:tony@xxxxxxxxxxx] > >* Gupta, Pekon <pekon@xxxxxx> [140519 21:07]: > >> From: Tony Lindgren [mailto:tony@xxxxxxxxxxx] > >> >* Pekon Gupta <pekon@xxxxxx> [140519 02:16]: > >> >> Adds pinmux and DT node for Micron (MT29F4G08AB) x8 NAND device present on > >> >> am437x-gp-evm board. > >> >> (1) As NAND Flash data lines are muxed with eMMC, Thus at a given time either > >> >> eMMC or NAND can be enabled. Selection between eMMC and NAND is controlled: > >> >> (a) By dynamically driving following GPIO pin from software > >> >> SPI2_CS0(GPIO) == 0 NAND is selected (default) > >> >> SPI2_CS0(GPIO) == 1 eMMC is selected > >> >> (b) By statically using Jumper (J89) on the board > >> > > >> >So which MMC controller has eMMC then? How do we select which one we > >> >have enabled in the am437x-gp-evm.dts by default? > >> > > >> If there is no Jumper on the board, then driving SPI2_CS0 before device > >> probe decides the selection between NAND and eMMC. Therefore NAND > >> pin-mux also includes SPI2_CS0 and enables PULLDOWN on it to select NAND. > > > >So do they share lines outside omap, not inside omap? > > > >The reason I'm asking is I'm worried about the conflicting > >pinctrl settings if we try to use both. And I guess that's > >not an issue if the muxing of lines is done outside the > >omap? > > > Yes, the muxing is outside OMAP SoC, so if SPI2_CS0 is correctly > driven it will not allow contention on GPMC line (as per board design). > > On am437x-gp-evm board, SPI2_CS0 is used to: > - route GPMC signals to selected device {eMMC | NAND}. > - keep the de-selected device {eMMC | NAND} in reset. OK thanks for clarifying that, applying into omap-for-v3.16/dt-v2. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
