Hi,
On 03/03/2014 08:04 PM, Tomasz Figa wrote:
On 03.03.2014 19:57, Javi Merino wrote:
Hi,
Commit fcb0ee6a3d (clk: Implement clk_unregister) added calls to
kref_get() and kref_put() to __clk_get() and __clk_put() without
checking if clk is not NULL:
@@ -1987,6 +2097,7 @@ int __clk_get(struct clk *clk)
if (clk && !try_module_get(clk->owner))
return 0;
+ kref_get(&clk->ref);
return 1;
}
@@ -1995,6 +2106,10 @@ void __clk_put(struct clk *clk)
if (WARN_ON_ONCE(IS_ERR(clk)))
return;
+ clk_prepare_lock();
+ kref_put(&clk->ref, __clk_release);
+ clk_prepare_unlock();
+
if (clk)
module_put(clk->owner);
}
Before this commit, these functions allowed clk to be NULL. In
particular, the "if (clk)" in __clk_put() is now useless, as clk has
been dereferenced by the time you reach it.
This causes Arndale Octa to panic on boot:
8<---
[ 7.430000] Creating amba device /amba/pdma@121B0000
[ 7.435000] create child: /amba/mdma@10800000
[ 7.440000] Creating amba device /amba/mdma@10800000
[ 7.445000] Unable to handle kernel NULL pointer dereference at virtual address 00000050
[ 7.450000] pgd = c0004000
[ 7.450000] [00000050] *pgd=00000000
[ 7.455000] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
[ 7.455000] Modules linked in:
[ 7.455000] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc3-00003-gb6026fe-dirty #23
[ 7.455000] task: ee0a8000 ti: ee0a6000 task.ti: ee0a6000
[ 7.455000] PC is at __clk_get+0x24/0x84
[ 7.455000] LR is at of_clk_get+0x5c/0x74
[...]
[ 7.455000] [<c02e5cc8>] (__clk_get) from [<c02e34b8>] (of_clk_get+0x5c/0x74)
[ 7.455000] [<c02e34b8>] (of_clk_get) from [<c02e350c>] (of_clk_get_by_name+0x3c/0xb0)
[ 7.455000] [<c02e350c>] (of_clk_get_by_name) from [<c02e35a4>] (clk_get+0x24/0x44)
[ 7.455000] [<c02e35a4>] (clk_get) from [<c01ee6fc>] (amba_get_enable_pclk+0x10/0x60)
[ 7.455000] [<c01ee6fc>] (amba_get_enable_pclk) from [<c01ee7ec>] (amba_device_add+0xa0/0x1e0)
[ 7.455000] [<c01ee7ec>] (amba_device_add) from [<c02e0f94>] (of_platform_bus_create+0x190/0x308)
[ 7.455000] [<c02e0f94>] (of_platform_bus_create) from [<c02e103c>] (of_platform_bus_create+0x238
[ 7.455000] [<c02e103c>] (of_platform_bus_create) from [<c02e116c>] (of_platform_populate+0x60/0x
[ 7.455000] [<c02e116c>] (of_platform_populate) from [<c04cc280>] (customize_machine+0x1c/0x40)
[ 7.455000] [<c04cc280>] (customize_machine) from [<c00088e8>] (do_one_initcall+0xe4/0x140)
[ 7.455000] [<c00088e8>] (do_one_initcall) from [<c04c9c50>] (kernel_init_freeable+0xfc/0x1c8)
[ 7.455000] [<c04c9c50>] (kernel_init_freeable) from [<c038447c>] (kernel_init+0x8/0xe4)
[ 7.455000] [<c038447c>] (kernel_init) from [<c000e4b8>] (ret_from_fork+0x14/0x3c)
[ 7.455000] Code: e3500000 08bd8010 e2843050 f57ff05b (e1932f9f)
[ 7.460000] ---[ end trace fe5cfa405506a77d ]---
[ 7.460000] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
8<---
I've tried putting "if (clk)" around the calls to kref_get() and
kref_put(), but that makes the Octa fail to boot like 3.13 did: when
tries to mount root.
What works for me so far is to remove the offending nodes from the DT:
8<---
diff --git a/arch/arm/boot/dts/exynos5420.dtsi b/arch/arm/boot/dts/exynos5420.dtsi
index 8db792b..c4ab992 100644
--- a/arch/arm/boot/dts/exynos5420.dtsi
+++ b/arch/arm/boot/dts/exynos5420.dtsi
@@ -303,27 +303,6 @@
#dma-requests = <32>;
};
- mdma0: mdma@10800000 {
- compatible = "arm,pl330", "arm,primecell";
- reg = <0x10800000 0x1000>;
- interrupts = <0 33 0>;
- clocks = <&clock 473>;
- clock-names = "apb_pclk";
- #dma-cells = <1>;
- #dma-channels = <8>;
- #dma-requests = <1>;
- };
-
- mdma1: mdma@11C10000 {
- compatible = "arm,pl330", "arm,primecell";
- reg = <0x11C10000 0x1000>;
- interrupts = <0 124 0>;
- clocks = <&clock 442>;
- clock-names = "apb_pclk";
- #dma-cells = <1>;
- #dma-channels = <8>;
- #dma-requests = <1>;
- };
};
spi_0: spi@12d20000 {
8<---
With this the Arndale Octa boots. This issue is present from 3.14-rc1
to 3.14-rc5. Any idea how this should be properly fixed in mainline?
This should be fixed with [1], which was supposed to be merged for
3.14-rc5. Mike?
[1] https://git.linaro.org/people/mike.turquette/linux.git/commit/00efcb1c8e1c3c5e5d3ce6f0682d66402911a84f
You may also want to consider this patch:
https://patchwork.kernel.org/patch/3597711
It looks like there is no clock registered for the mdm0 PL330 device
in exynos5420 clocks driver (drivers/clk/samsung/clk-exynos5420.c).
So a proper fix, except of a patch pointed out by Tomasz, would be to
add a corresponding entry to exynos5420_gate_clocks[] array (the mdm0
gate clock seems to be already documented in Documentation/devicetree/
bindings/clock/exynos5420-clock.txt).
AFAIU, you're still having problems even with patch [1] applied ?
--
Regards,
Sylwester
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