On 08/01/2014 09:38 AM, Tony Lindgren wrote: > * Roger Quadros <rogerq@xxxxxx> [140731 04:46]: >> +Sourav for QSPI and Balaji for mmc >> >> On 07/30/2014 10:40 PM, Pekon Gupta wrote: >>> Hi Roger, >>> >>> On Tue, Jul 29, 2014 at 5:45 PM, Roger Quadros <rogerq@xxxxxx> wrote: >>>> On 07/23/2014 01:58 PM, Pekon Gupta wrote: >>>>> This patch adds support for parallel NOR device (S29GL512S10) present on J6-EVM. >>>>> The Flash device is connected to GPMC controller on chip-select[0] and accessed >>>>> as memory-mapped device. It has data-witdh=x16, capacity-64MBytes(512Mbits) and >>>>> is CFI compatible. >>>>> As multiple devices are share GPMC pins on this board, so following board >>>>> settings are required to detect NOR device: >>>>> SW5.1 (NAND_BOOTn) = OFF (logic-1) >>>>> SW5.2 (NOR_BOOTn) = ON (logic-0) /* Active-low */ >>>>> SW5.3 (eMMC_BOOTn) = OFF (logic-1) >>>>> SW5.4 (QSPI_BOOTn) = OFF (logic-1) >>>> >>>> Why does NOR have any dependency on states of eMMC_BOOTn and QSPI_BOOTn? >>>> >>> If you see the schematics of J6-EVM, GPMC data and control lines are shared >>> between NAND, NOR, eMMC (and probably QSPI also). >>> I don't have access to TI's hardaware or board schematics anymore, so >>> please double check. >> >> I just took a deeper look in the schematics. >> It has nothing to do with GPMC Data and control lines but with the address lines. >> The GPMC address lines are muxed on the same pins of the SoC as QSPI and MMC2. >> i.e. A13-A18,CS2 for QSPI and A19-A27,CS1 for MMC2 >> >> NAND can probably work simultaneously with QSPI and MMC2 but for NOR case, QSPI and MMC2 >> need to be disabled. >> >> This is starting to look ugly where apart from changing the DIP switch the DTS has to be >> hand modified to support a certain case. >> >> Lets leave the most usable configuration for default case i.e. NAND, QSPI and MMC2 enabled and keep NOR information in the dts but keep it disabled with a note that if NOR is enabled then NAND, QSPI, and MMC2 nodes need to be disabled. >> >> I will resend this patch with the relevant changes. > > It might make sense for the gpmc driver to manage the pins in some > cases. That would allow dynamic muxing of the pins depending which > driver is loaded, or even during runtime if needed. It is more like a board configuration so something more generic than the gpmc driver has to manage. Also, QSPI and MMC don't fall under GPMC scope. There are 2 things that need to change to update the hardware configuration. 1) The pinmux via the enabling/disabling (or plugging in/out) of relevant nodes in the DT. 2) The I2C GPIOs which reconfigure the DIP Switch lines in order to reconfigure external Muxes. cheers, -roger -- 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
