On Thu, Apr 25, 2019 at 06:51:11AM +0000, Anson Huang wrote: > Hi, Guenter > > > -----Original Message----- > > From: Guenter Roeck [mailto:groeck7@xxxxxxxxx] On Behalf Of Guenter > > Roeck > > Sent: Thursday, April 25, 2019 10:15 AM > > To: Anson Huang <anson.huang@xxxxxxx>; shawnguo@xxxxxxxxxx; > > s.hauer@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; > > wim@xxxxxxxxxxxxxxxxxx; Aisheng Dong <aisheng.dong@xxxxxxx>; linux- > > arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux- > > watchdog@xxxxxxxxxxxxxxx > > Cc: dl-linux-imx <linux-imx@xxxxxxx> > > Subject: Re: [PATCH 1/2] firmware: imx: SCU irq should ONLY be enabled > > after SCU IPC is ready > > > > On 4/24/19 6:14 PM, Anson Huang wrote: > > > The imx_scu_irq_group_enable() is normally called during module driver > > > probe phase to enable SCU group irq, e.g., i.MX system controller > > > watchdog driver will call it during its driver probe phase, as i.MX > > > system controller watchdog driver does NOT need SCU IPC handle for > > > operations, so it could be probed before i.MX SCU IPC is ready, and > > > below dump will show out: > > > > > > [ 0.933001] Hardware name: Freescale i.MX8QXP MEK (DT) > > > [ 0.938129] pstate: 60000005 (nZCv daif -PAN -UAO) > > > [ 0.942907] pc : imx_scu_call_rpc+0x114/0x158 > > > [ 0.947251] lr : imx_scu_irq_group_enable+0x74/0xc4 > > > [ 0.952113] sp : ffff00001005bae0 > > > [ 0.955415] x29: ffff00001005bae0 x28: ffff0000111bb0a0 > > > [ 0.960712] x27: ffff00001140b000 x26: ffff00001111068c > > > [ 0.966011] x25: ffff0000111bb100 x24: 0000000000000000 > > > [ 0.971311] x23: ffff0000113d9cd8 x22: 0000000000000001 > > > [ 0.976610] x21: 0000000000000001 x20: ffff80083b51a410 > > > [ 0.981909] x19: ffff000011259000 x18: 0000000000000480 > > > [ 0.987209] x17: 000000000023ffb8 x16: 0000000000000010 > > > [ 0.992508] x15: 000000000000023f x14: ffffffffffffffff > > > [ 0.997807] x13: 0000000000000018 x12: 0000000000000030 > > > [ 1.003107] x11: 0000000000000003 x10: 0101010101010101 > > > [ 1.008406] x9 : ffffffffffffffff x8 : 7f7f7f7f7f7f7f7f > > > [ 1.013706] x7 : fefefeff646c606d x6 : 0000000000000000 > > > [ 1.019005] x5 : ffff0000112596c8 x4 : 0000000000000008 > > > [ 1.024304] x3 : 0000000000000003 x2 : 0000000000000001 > > > [ 1.029604] x1 : ffff00001005bb58 x0 : 0000000000000000 > > > [ 1.034905] Call trace: > > > [ 1.037341] imx_scu_call_rpc+0x114/0x158 > > > [ 1.041334] imx_scu_irq_group_enable+0x74/0xc4 > > > [ 1.045856] imx_sc_wdt_probe+0x24/0x150 > > > [ 1.049766] platform_drv_probe+0x4c/0xb0 > > > [ 1.053762] really_probe+0x1f8/0x2c8 > > > [ 1.057407] driver_probe_device+0x58/0xfc > > > [ 1.061490] device_driver_attach+0x68/0x70 > > > [ 1.065660] __driver_attach+0x94/0xdc > > > [ 1.069397] bus_for_each_dev+0x64/0xc0 > > > [ 1.073220] driver_attach+0x20/0x28 > > > [ 1.076782] bus_add_driver+0x148/0x1fc > > > [ 1.080601] driver_register+0x68/0x120 > > > [ 1.084424] __platform_driver_register+0x4c/0x54 > > > [ 1.089120] imx_sc_wdt_driver_init+0x18/0x20 > > > [ 1.093463] do_one_initcall+0x58/0x1b8 > > > [ 1.097287] kernel_init_freeable+0x1cc/0x288 > > > [ 1.101630] kernel_init+0x10/0x100 > > > [ 1.105101] ret_from_fork+0x10/0x18 > > > [ 1.108669] ---[ end trace 9e03302114457de9 ]--- > > > [ 1.113296] enable irq failed, group 1, mask 1, ret -22 > > > > > > To avoid such scenario, return -EPROBE_DEFER in > > > imx_scu_irq_group_enable() API if SCU IPC is NOT ready, then module > > > driver which calls this API in probe phase will defer probe after SCU IPC > > ready. > > > > > Difficult to comment - I seem to have missed the patch introducing the call to > > imx_scu_irq_group_enable() from the watchdog driver, and I don't see it in - > > next either. > > > > However, as far as I can see, imx_sc_irq_ipc_handle is initialized from > > imx_scu_probe(). If the watchdog driver depends on it, it should be a sub- > > node of fsl,imx-scu, and be instantiated from the call to > > devm_of_platform_populate() in imx_scu_probe(). This should make the > > EPROBE_DEFER unnecessary. > > > > In other words, the above statement "i.MX system controller watchdog > > driver does NOT need SCU IPC handle for operations" is no longer accurate. > > If it needs the interrupt, and the interrupt needs the IPC handle, the > > watchdog driver does require the IPC handle. It would otherwise not need to > > defer its probe function until the IPC handle is available. > > > > I would like to add that it is highly unusual for a watchdog driver to depend > > on a firmware driver. However, again, that is difficult to argue since I seem to > > have missed the patch series introducing that dependency. > > I agreed watchdog should be a sub-node of SCU if it depends ON it, but as this API is > exposed, I think adding such check is necessary, we do NOT know when this API could > be called, so this protection should be necessary, it is just because I met this issue > during adding pretimeout function of i.MX SC wdog, so I put the patches together. > I agree that the check is necessary for imx_scu_irq_group_enable(). But the watchdog driver should still only be instantiated after (or, rather, from) its parent driver since that is now the well defined initialization order. Guenter > Thanks, > Anson > > > > > Guenter > > > > > Fixes: 851826c7566e ("firmware: imx: enable imx scu general irq > > > function") > > > Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx> > > > --- > > > drivers/firmware/imx/imx-scu-irq.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/drivers/firmware/imx/imx-scu-irq.c > > > b/drivers/firmware/imx/imx-scu-irq.c > > > index 043833a..687121f 100644 > > > --- a/drivers/firmware/imx/imx-scu-irq.c > > > +++ b/drivers/firmware/imx/imx-scu-irq.c > > > @@ -100,6 +100,9 @@ int imx_scu_irq_group_enable(u8 group, u32 mask, > > u8 enable) > > > struct imx_sc_rpc_msg *hdr = &msg.hdr; > > > int ret; > > > > > > + if (!imx_sc_irq_ipc_handle) > > > + return -EPROBE_DEFER; > > > + > > > hdr->ver = IMX_SC_RPC_VERSION; > > > hdr->svc = IMX_SC_RPC_SVC_IRQ; > > > hdr->func = IMX_SC_IRQ_FUNC_ENABLE; > > > >
