Hi Vikas,
On 25.04.2014 10:05, Vikas Sajjan wrote:
Hi,
On Thu, Apr 24, 2014 at 9:37 PM, Tomasz Figa <t.figa@xxxxxxxxxxx> wrote:
Hi Chanho,
On 14.04.2014 14:48, Chanho Park wrote:
This patch adds a PMU(Power Management Unit) syscon node. This
should be required for USB Phy syscon regmap I/F.
Cc: Tomasz Figa <t.figa@xxxxxxxxxxx>
Cc: Kamil Debski <k.debski@xxxxxxxxxxx>
Signed-off-by: Chanho Park <chanho61.park@xxxxxxxxxxx>
---
arch/arm/boot/dts/exynos4.dtsi | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/arm/boot/dts/exynos4.dtsi
b/arch/arm/boot/dts/exynos4.dtsi
index 2f8bcd0..e565b86 100644
--- a/arch/arm/boot/dts/exynos4.dtsi
+++ b/arch/arm/boot/dts/exynos4.dtsi
@@ -110,6 +110,11 @@
reg = <0x10010000 0x400>;
};
+ pmu_reg: syscon@10020000 {
+ compatible = "samsung,exynos4-pmureg", "syscon";
Assume a case where exynos PMU is made as platform driver [1] and we
need use the compatible "samsung,exynos4-pmureg" in the driver.
But since syscon driver uses compatible "syscon" and once the syscon
driver is probed, the exynos PMU platform driver [1] will NEVER be
probed.
So my question is, can we have 2 compatible strings for a DT node, and
both the compatible strings are used for probing purpose?
Recently I faced this issue on exynos5250, where i was testing PMU
driver [1] and I noticed that PMU driver [1] was NEVER probed, if I
enable syscon driver in menuconfig.
No, it is not possible to bind two drivers with different compatible
strings to the same node. Basically this is because only one platform
driver can be bound to particular platform device.
The rule is that the most specific compatible string (e.g. the first
from the left) that matches should be used, but I'm not sure if this is
implemented this way in Linux kernel, especially considering that a
platform driver usually probes when it is being registered. So we might
have a race here, which you can work around by making sure that your PMU
driver is always registered first (e.g. by lowering its initcall level).
Best regards,
Tomasz
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