On Mon, Mar 04, 2024 at 04:04:08PM +0100, Andi Shyti wrote:
> Hi Jesper,
Hi Andi,
> On Mon, Mar 04, 2024 at 12:01:14PM +0100, Jesper Nilsson wrote:
> > devm_request_irq() is called before we initialize the "variant"
> > member variable from of_device_get_match_data(), so if an interrupt
> > is triggered inbetween, we can end up following a NULL pointer
> > in the interrupt handler.
> >
> > This problem was exposed when the I2C controller in question was
> > (mis)configured to be used in both secure world and Linux.
> >
> > That this can happen is also reflected by the existing code that
> > clears any pending interrupts from "u-boot or misc causes".
> >
> > Move the clearing of pending interrupts and the call to
> > devm_request_irq() to the end of probe.
>
> I'm OK with moving the irq request at the end and I'm going to
> give my r-b anyway. There is still one comment below.
Thanks.
> > Additionally, return failure if we can't find a match in devicetree.
> >
> > Signed-off-by: Jesper Nilsson <jesper.nilsson@xxxxxxxx>
>
> The way you are describing it you would need the Fixes tag here
> and this patch should be treated as a fix.
Ok, the variant member was introduced in:
218e1496135e ("i2c: exynos5: add support for HSI2C on Exynos5260 SoC")
Before that, the ordering didn't matter.
> Nevertheless, I think that it's odd that the device is sending
> interrupts at this phase and the real fix should be preventing
> the controller to send interrupts here.
I found this bug when we moved control of an I2C bus into secure
world (OP-TEE) and hadn't removed it from devicetree config.
Since we hadn't enabled the secure parts yet, the kernel could still get
the interrupt, even when OP-TEE was performing I2C transfers.
> How have you tested this patch?
This was tested in our ARTPEC-8 SoC, which includes the same IP the
exynos SoCs, both with and without the problematic configuration
described above.
> > ---
> > drivers/i2c/busses/i2c-exynos5.c | 32 ++++++++++++++++++--------------
> > 1 file changed, 18 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
> > index 385ef9d9e4d4..eba717e5cad7 100644
> > --- a/drivers/i2c/busses/i2c-exynos5.c
> > +++ b/drivers/i2c/busses/i2c-exynos5.c
> > @@ -906,24 +906,14 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
> > i2c->adap.algo_data = i2c;
> > i2c->adap.dev.parent = &pdev->dev;
> >
> > - /* Clear pending interrupts from u-boot or misc causes */
> > - exynos5_i2c_clr_pend_irq(i2c);
> > -
> > spin_lock_init(&i2c->lock);
> > init_completion(&i2c->msg_complete);
> >
> > - i2c->irq = ret = platform_get_irq(pdev, 0);
> > - if (ret < 0)
> > - goto err_clk;
> > -
> > - ret = devm_request_irq(&pdev->dev, i2c->irq, exynos5_i2c_irq,
> > - IRQF_NO_SUSPEND, dev_name(&pdev->dev), i2c);
> > - if (ret != 0) {
> > - dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n", i2c->irq);
> > - goto err_clk;
> > - }
> > -
> > i2c->variant = of_device_get_match_data(&pdev->dev);
> > + if (!i2c->variant) {
> > + dev_err(&pdev->dev, "can't match device variant\n");
> > + return -ENODEV;
>
> return dev_err_probe(), please.
Will do.
> Andi
/^JN - Jesper Nilsson
--
Jesper Nilsson -- jesper.nilsson@xxxxxxxx
