On Thursday 07 January 2016 16:24:22 Brijesh Singh wrote: > >> + > >> +Examples: > >> + sata0@e0300000 { > >> + compatible = "amd,seattle-ahci"; > >> + reg = <0x0 0xe0300000 0x0 0xf0000>, <0x0 0xe0000078 0x0 0x1>; > > > > Looking at the register values, I doubt that the SGPIO is actually part of the > > sata device. More likely, you are pointing in the middle of an actual > > GPIO controller. > > > > That address is SGPIO control register for SATA. The current hardware implementation to control activity LED is not ideal. Of course its a control register "for" SATA, what I meant is that it's not part "of" the SATA IP block, which is hopefully a standard AHCI compliant part as required by SBSA. > A57 does not have access to GPIO's connected to backplane controller > instead SoC has exposed two SGPIO control registers (LSIOC_SGPIO_CONTROL0: > 0xE000_0078 and LSIOC_SGPIO_CONTROL1: 0xE000_007C) to A57. All we > need to do is to program these registers based on the disk activity. > The firmware running on A5 reads the values and generate proper SGPIO > timing and toggles the LEDs etc. It still sounds like SGPIO is not part of the AHCI standard spec, but rather a subset of a device called LSIOC. > These registers are defined in SATA0/1 DSDT resource template and also > documented in SoC BKDG. I just noticed that BKDG has wrong register > definition so will ask documentation folks to fix that. > > This driver is using SGPIO LED control similar to sata_highbank [1] > except bit bang GPIO (which is done by firmware). > > [1] http://lxr.free-electrons.com/source/drivers/ata/sata_highbank.c#L140 This one is rather different: there is a single device that combines registers for AHCI, the PHY attached to it and the LED. This is not SBSA compliant of course, and it requires having a special driver. What you have instead looks like a regular AHCI implementation that should just work with the standard driver as long as you describe how it gets its LEDs. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html