Hi Tejun, On some SOCs PORTS_IMPL register value is never programmed by the BIOS and left at zero value. Which means that no sata ports are available for software. AHCI driver used to cope up with this by fabricating the port_map if the PORTS_IMPL register is read zero, but recent patch [1] broke this workaround as zero value was valid for nvme disks. This patch adds ports-implemented dt bindings as workaround for this issue in a way that DT can dictate the port_map incase where the SOCs does not program it already. Am sure that there are more than one SOC that hits this issue. Without this patchset, ACHI on APQ8064 Qualcomm platform is broken in mainline. With the below patchset am able to get back the functionality. Can you pick the first 2 patches via libata tree, I can request Andy Gross to take dts patch via arm-soc tree. Changes since RFC: - Remove DT example as suggested by Rob. - Fixed comments on DT binding patch as suggested by Rob. - removed unused variable spotted by kernel test robot. Thanks, srini [1] 566d18 "libata: disable forced PORTS_IMPL for >= AHCI 1.3" Srinivas Kandagatla (3): libahci: save port map for forced port map ata: ahci-platform: Add ports-implemented DT bindings. ARM: dts: apq8064: add ahci ports-implemented mask Documentation/devicetree/bindings/ata/ahci-platform.txt | 4 ++++ arch/arm/boot/dts/qcom-apq8064.dtsi | 3 ++- drivers/ata/ahci_platform.c | 3 +++ drivers/ata/libahci.c | 1 + 4 files changed, 10 insertions(+), 1 deletion(-) -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
