Re: [PATCH 4/4] clk: zynq: Use of_init_clk_data()

From: Stephen Boyd <sboyd@codeaurora.org>
To: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Mike Turquette <mturquette@linaro.org>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Josh Cartwright <josh.cartwright@ni.com>
Subject: Re: [PATCH 4/4] clk: zynq: Use of_init_clk_data()
Date: Wed, 19 Dec 2012 12:30:21 -0800	[thread overview]
Message-ID: <50D223DD.8070208@codeaurora.org> (raw)
In-Reply-To: <b11edd0b-27ff-48b3-9f2a-1e7ab293cc34@CO9EHSMHS019.ehs.local>

On 12/19/12 11:22, Soren Brinkmann wrote:
> Hi Stephen,
>
> I guess Josh is the better person to talk about this, since he created the
> patches regarding common clock for mainline, but I tried running your series
> and ran into this:
>
> Unable to handle kernel NULL pointer dereference at virtual address 0000002a
> pgd = c0004000
> [0000002a] *pgd=00000000
> Internal error: Oops: 5 [#1] PREEMPT ARM
> Modules linked in:
> CPU: 0    Tainted: G        W     (3.7.0-rc3-00025-gc11ffdd-dirty #246)
> PC is at __clk_prepare+0x20/0x80
> LR is at clk_prepare+0x2c/0x44
> pc : [<c031659c>]    lr : [<c0316628>]    psr: a0000153
> sp : ee02fdd0  ip : ee02fde8  fp : ee02fde4
> r10: 00000000  r9 : 00000000  r8 : c0587884
> r7 : 00000000  r6 : c05aab98  r5 : fffffffe  r4 : fffffffe
> r3 : 00000000  r2 : 00000000  r1 : 00000000  r0 : fffffffe
> Flags: NzCv  IRQs on  FIQs off  Mode SVC_32  ISA ARM  Segment kernel
> Control: 18c5387d  Table: 00004059  DAC: 00000015
> Process swapper (pid: 1, stack limit = 0xee02e230)
> Stack: (0xee02fdd0 to 0xee030000)
> fdc0:                                     c05b6a18 fffffffe ee02fdfc ee02fde8
> fde0: c0316628 c0316588 ee085400 fffffffe ee02fe24 ee02fe00 c03c1358 c0316608
> fe00: c03c1328 ee085410 c05aab98 c05aab98 00000000 c0587884 ee02fe34 ee02fe28
> fe20: c026a5c0 c03c1334 ee02fe5c ee02fe38 c0268f50 c026a5a8 c026a7b8 c0313ac0
> fe40: ee085410 ee085410 ee085444 c05aab98 ee02fe7c ee02fe60 c02691c0 c0268e18
> fe60: c0269150 c05aab98 c0269150 00000000 ee02fea4 ee02fe80 c0267320 c026915c
> fe80: ee00948c ee096df0 c021e02c c05aab98 ed9a0bc0 c05ab3a8 ee02feb4 ee02fea8
> fea0: c0268a28 c02672d0 ee02fee4 ee02feb8 c0268408 c0268a0c c04b56d1 00000000
> fec0: ee02fee4 c05aab98 c0565e60 00000000 0000006f c0587884 ee02ff14 ee02fee8
> fee0: c0269990 c0268340 00000000 00000000 c0565e60 00000000 0000006f c0587884
> ff00: 00000000 00000000 ee02ff24 ee02ff18 c026a9cc c02698f0 ee02ff3c ee02ff28
> ff20: c0565e84 c026a984 ee02e000 ee02ff40 ee02ff74 ee02ff40 c00086f8 c0565e6c
> ff40: c04f72e4 00000000 ee02ff74 00000006 00000006 c0571dac c0571d8c 0000006f
> ff60: c0587884 00000000 ee02ffac ee02ff78 c03bf9c4 c0008664 00000006 00000006
> ff80: c05511a8 00000000 ee02ffac 00000000 c03bf8cc 00000000 00000000 00000000
> ffa0: 00000000 ee02ffb0 c000ea98 c03bf8d8 00000000 00000000 00000000 00000000
> ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> ffe0: 00000000 00000000 00000000 00000000 00000013 00000000 0158ec21 0eced1ff
> [<c031659c>] (__clk_prepare+0x20/0x80) from [<c0316628>] (clk_prepare+0x2c/0x44)
> [<c0316628>] (clk_prepare+0x2c/0x44) from [<c03c1358>] (xuartps_probe+0x30/0x1ac
> )
> [<c03c1358>] (xuartps_probe+0x30/0x1ac) from [<c026a5c0>] (platform_drv_probe+0x
> 24/0x28)
> [<c026a5c0>] (platform_drv_probe+0x24/0x28) from [<c0268f50>] (driver_probe_devi
> ce+0x144/0x344)
> [<c0268f50>] (driver_probe_device+0x144/0x344) from [<c02691c0>] (__driver_attac
> h+0x70/0x94)
> [<c02691c0>] (__driver_attach+0x70/0x94) from [<c0267320>] (bus_for_each_dev+0x5
> c/0x8c)
> [<c0267320>] (bus_for_each_dev+0x5c/0x8c) from [<c0268a28>] (driver_attach+0x28/
> 0x30)
> [<c0268a28>] (driver_attach+0x28/0x30) from [<c0268408>] (bus_add_driver+0xd4/0x
> 254)
> [<c0268408>] (bus_add_driver+0xd4/0x254) from [<c0269990>] (driver_register+0xac
> /0x14c)
> [<c0269990>] (driver_register+0xac/0x14c) from [<c026a9cc>] (platform_driver_reg
> ister+0x54/0x68)
> [<c026a9cc>] (platform_driver_register+0x54/0x68) from [<c0565e84>] (xuartps_ini
> t+0x24/0x44)
> [<c0565e84>] (xuartps_init+0x24/0x44) from [<c00086f8>] (do_one_initcall+0xa0/0x
> 170)
> [<c00086f8>] (do_one_initcall+0xa0/0x170) from [<c03bf9c4>] (kernel_init+0xf8/0x
> 2ac)
> [<c03bf9c4>] (kernel_init+0xf8/0x2ac) from [<c000ea98>] (ret_from_fork+0x14/0x20
> )
> Code: e8bd4000 e2504000 01a05004 0a000015 (e594302c) 
> ---[ end trace 1b75b31a2719ed1d ]---
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>
>
> A probably unique thing I do is, I set the status of uart0 to disabled. This way
> I can reuse my rootfs which does not run getty on ttyPS1. And this worked fine
> before.
>

Thanks for testing. It seems that clocks are failing to register. Please
try this patch.

--->8-----

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 2be22a2..2734715 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -948,9 +948,9 @@ static int xuartps_probe(struct platform_device *pdev)
        struct clk *clk;

        clk = of_clk_get(pdev->dev.of_node, 0);
-       if (!clk) {
-               dev_err(&pdev->dev, "no clock specified\n");
-               return -ENODEV;
+       if (IS_ERR(clk)) {
+               dev_err(&pdev->dev, "failed to get clock\n");
+               return PTR_ERR(clk);
        }

        rc = clk_prepare_enable(clk);


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