Messages in this thread | | | Subject | Re: [PATCH 3/3] amba: Properly handle device probe without IRQ domain | From | Kefeng Wang <> | Date | Wed, 25 Aug 2021 16:39:48 +0800 |
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On 2021/8/25 16:04, Saravana Kannan wrote: > On Tue, Aug 24, 2021 at 9:05 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote: >> >> On 2021/8/25 4:08, Saravana Kannan wrote: >>> On Tue, Aug 24, 2021 at 1:05 PM Rob Herring <robh+dt@kernel.org> wrote: >>>> +Saravana >>>> >>>> Saravana mentioned to me there may be some issues with this one... >>>> >>>> >>>> On Mon, Aug 16, 2021 at 2:43 AM Kefeng Wang <wangkefeng.wang@huawei.com> wrote: >>>>> of_amba_device_create() uses irq_of_parse_and_map() to translate >>>>> a DT interrupt specification into a Linux virtual interrupt number. >>>>> >>>>> But it doesn't properly handle the case where the interrupt controller >>>>> is not yet available, eg, when pl011 interrupt is connected to MBIGEN >>>>> interrupt controller, because the mbigen initialization is too late, >>>>> which will lead to no IRQ due to no IRQ domain found, log is shown below, >>>>> "irq: no irq domain found for uart0 !" >>>>> >>>>> use of_irq_get() to return -EPROBE_DEFER as above, and in the function >>>>> amba_device_try_add()/amba_device_add(), it will properly handle in such >>>>> case, also return 0 in other fail cases to be consistent as before. >>>>> >>>>> Cc: Russell King <linux@armlinux.org.uk> >>>>> Cc: Rob Herring <robh+dt@kernel.org> >>>>> Cc: Frank Rowand <frowand.list@gmail.com> >>>>> Reported-by: Ruizhe Lin <linruizhe@huawei.com> >>>>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> >>>>> --- >>>>> drivers/amba/bus.c | 27 +++++++++++++++++++++++++++ >>>>> drivers/of/platform.c | 6 +----- >>>>> 2 files changed, 28 insertions(+), 5 deletions(-) >>>>> >>>>> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c >>>>> index 36f2f42c8014..720aa6cdd402 100644 >>>>> --- a/drivers/amba/bus.c >>>>> +++ b/drivers/amba/bus.c >>>>> @@ -19,6 +19,7 @@ >>>>> #include <linux/clk/clk-conf.h> >>>>> #include <linux/platform_device.h> >>>>> #include <linux/reset.h> >>>>> +#include <linux/of_irq.h> >>>>> >>>>> #include <asm/irq.h> >>>>> >>>>> @@ -371,12 +372,38 @@ static void amba_device_release(struct device *dev) >>>>> kfree(d); >>>>> } >>>>> >>>>> +static int of_amba_device_decode_irq(struct amba_device *dev) >>>>> +{ >>>>> + struct device_node *node = dev->dev.of_node; >>>>> + int i, irq = 0; >>>>> + >>>>> + if (IS_ENABLED(CONFIG_OF_IRQ) && node) { >>>>> + /* Decode the IRQs and address ranges */ >>>>> + for (i = 0; i < AMBA_NR_IRQS; i++) { >>>>> + irq = of_irq_get(node, i); >>>>> + if (irq < 0) { >>>>> + if (irq == -EPROBE_DEFER) >>>>> + return irq; >>>>> + irq = 0; >>>>> + } >>>>> + >>>>> + dev->irq[i] = irq; >>>>> + } >>>>> + } >>>>> + >>>>> + return 0; >>>>> +} >>>>> + >>>>> static int amba_device_try_add(struct amba_device *dev, struct resource *parent) >>>>> { >>>>> u32 size; >>>>> void __iomem *tmp; >>>>> int i, ret; >>>>> >>>>> + ret = of_amba_device_decode_irq(dev); >>>>> + if (ret) >>>>> + goto err_out; >>>>> + >>> Similar to other resources the AMBA bus "gets" for the device, I think >>> this should be moved into amba_probe() and not here. There's no reason >>> to delay the addition of the device (and loading its module) because >>> the IRQ isn't ready yet. >> The following code in the amba_device_try_add() will be called, it uses irq[0] >> and irq[1], so I put of_amba_device_decode_irq() into amba_device_try_add(). >> >> 470 if (dev->irq[0]) >> 471 ret = device_create_file(&dev->dev, &dev_attr_irq0); >> 472 if (ret == 0 && dev->irq[1]) >> 473 ret = device_create_file(&dev->dev, &dev_attr_irq1); >> 474 if (ret == 0) >> 475 return ret; >> >> of_amba_device_decode_irq() in amba_device_try_add() won't lead to issue, >> only delay the device add, right? > But delaying the device add is the issue. For example, adding a device > could trigger the loading of the corresponding module using uevents. > But now this change would delay that step. That can have other > unintended consequences -- slowing down boot, what if the driver was > working fine without the IRQ, etc. > >> If make it into amba_probe(), the above code should be moved too, could we >> make a new patch to move both of them, or don't move them? > I'd say move them both. If Russell hasn't already picked this up, then > I'd say redo your Patch 3/3.
Sure,I will update it and resend.
> > Btw, I've been working on [1] cleaning up the one-off deferred probe > solution that we have for amba devices. That causes a bunch of other > headaches. Your patch 3/3 takes us further in the wrong direction by > adding more reasons for delaying the addition of the device. Thanks for your explanation. > -Saravana > > [1] - https://lore.kernel.org/lkml/CAGETcx8b228nDUho3cX9AAQ-pXOfZTMv8cj2vhdx9yc_pk8q+A@mail.gmail.com/ > . >
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