(Old thread name: Exynos4210: fix power domain for MDMA1 device) This patchset fixes mysterious boot hang on Exynos 4210 SoCs, when IOMMU is enabled. There is no direct dependency between IOMMU devices and MDMA1. However enabling IOMMU changes the device probe order, what results in LCD0 power domain being turned off for some time. During that time the registration of MDMA1 device happens, what results in system hangs, because the common bus code tries to read PID/CID registers from turned-off device. Since the proposed change in the driver core had impact on existing drivers (see '-next regression: "driver cohandle -EPROBE_DEFER from bus_type.match()"' thread https://lkml.org/lkml/2015/12/17/390 ), I've checked all the functions assigned to match callback of struct bus_type objects and found that there are only 4 such functions that don't return 0/1 values: 1. arch/arm/common/sa1111.c: sa1111_match -> result of bitwise & 2. drivers/nvdimm/bus.c: nvdimm_bus_match -> result of test_bit() 3. drivers/sh/superhyway/superhyway.c: superhyway_bus_match -> error codes (this is really funny case, all errors are resolved to 'matched' case) 4. drivers/staging/unisys/visorbus/visorbus_main.c: visorbus_match -> 0 and some positive integer values, safe for now The list of functions that I've examined has been generated by following shell command: $ git grep -Pp "\.match\s" | grep -A1 bus_type | grep "\.match\s" | tr -s "\t;&,=:" " " | cut -d" " -f1,3 Only the first two functions require potential fixing to ensure that correct match will not result in negative return value, so the 2 additional patches have been added to v5 patchset. Best regards Marek Szyprowski Samsung R&D Institute Poland Changelog: v5: - added 2 more patches to avoid regression with existing drivers (nvdimm and sa1111), for more information, see https://lkml.org/lkml/2015/12/17/390 - changed thread name to "AMBA: add complete support for power domains" v4: https://lkml.org/lkml/2015/12/2/52 - fixed more issues pointed by Ulf Hansson and Russell King v3: https://lkml.org/lkml/2015/12/1/334 - fixed issues pointed by Ulf Hansson - dropped patch for exynos4210 dts, because it already got queued for merging v2: https://lkml.org/lkml/2015/11/26/229 - added 2 patches from 'On-demand device probing' thread (https://lkml.org/lkml/2015/9/29/189), which move PID/CIR reading from amba_device_add() to amba_match() - moved dev_pm_domain_attach() to amba_match(), which is allowed to return -EPROBE_DEFER v1: http://www.spinics.net/lists/arm-kernel/msg463185.html - initial version Patch summary: Dan Williams (1): drivers: nvdimm: ensure no negative value gets returned on positive match Marek Szyprowski (2): ARM: sa1111: ensure no negative value gets returned on positive match ARM: amba: Properly handle devices with power domains Tomeu Vizoso (2): driver core: handle -EPROBE_DEFER from bus_type.match() ARM: amba: Move reading of periphid to amba_match() Documentation/driver-model/porting.txt | 6 +- arch/arm/common/sa1111.c | 2 +- drivers/amba/bus.c | 152 ++++++++++++++++++--------------- drivers/base/dd.c | 24 +++++- drivers/nvdimm/bus.c | 2 +- include/linux/device.h | 7 +- 6 files changed, 114 insertions(+), 79 deletions(-) -- 1.9.2 -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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