On Fri, Jan 24, 2025 at 01:26:46PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Dec 30, 2024 at 01:24:25PM +0530, Mukesh Ojha wrote:
> > For some SoCs, boot firmware is using the same IPCC instance used
> > by Linux and it has kept CLEAR_ON_RECV_RD set which basically means
> > interrupt pending registers are cleared when RECV_ID is read and the
> > register automatically updates to the next pending interrupt/client
> > status based on priority.
> >
> > Clear the CLEAR_ON_RECV_RD if it is set from the boot firmware.
> >
>
> Any user visible implications due to this?
>
User visible impact is the case of missing interrupt.
We are accessing IPCC_REG_RECV_ID register both from qcom_ipcc_irq_fn()
and from qcom_ipcc_pm_resume() and for some reason if
qcom_ipcc_pm_resume() run just millisecond before qcom_ipcc_irq_fn after
assertion of interrupt from the remote, qcom_ipcc_pm_resume reads the
IPCC_REG_RECV_ID and clears it and when the same register read from the
qcom_ipcc_irq_fn() it does not see the interrupt.
> > Signed-off-by: Mukesh Ojha <mukesh.ojha@xxxxxxxxxxxxxxxx>
> > ---
> > Change in v2:
> > - Corrected email id in the Sob.
> >
> > drivers/mailbox/qcom-ipcc.c | 16 ++++++++++++++++
> > 1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/mailbox/qcom-ipcc.c b/drivers/mailbox/qcom-ipcc.c
> > index 14c7907c6632..0b17a38ea6bf 100644
> > --- a/drivers/mailbox/qcom-ipcc.c
> > +++ b/drivers/mailbox/qcom-ipcc.c
> > @@ -14,6 +14,7 @@
> > #include <dt-bindings/mailbox/qcom-ipcc.h>
> >
> > /* IPCC Register offsets */
> > +#define IPCC_REG_CONFIG 0x08
> > #define IPCC_REG_SEND_ID 0x0c
> > #define IPCC_REG_RECV_ID 0x10
> > #define IPCC_REG_RECV_SIGNAL_ENABLE 0x14
> > @@ -21,6 +22,7 @@
> > #define IPCC_REG_RECV_SIGNAL_CLEAR 0x1c
> > #define IPCC_REG_CLIENT_CLEAR 0x38
> >
> > +#define IPCC_CLEAR_ON_RECV_RD BIT(0)
> > #define IPCC_SIGNAL_ID_MASK GENMASK(15, 0)
> > #define IPCC_CLIENT_ID_MASK GENMASK(31, 16)
> >
> > @@ -274,6 +276,7 @@ static int qcom_ipcc_pm_resume(struct device *dev)
> > static int qcom_ipcc_probe(struct platform_device *pdev)
> > {
> > struct qcom_ipcc *ipcc;
> > + u32 config_value;
> > static int id;
> > char *name;
> > int ret;
> > @@ -288,6 +291,19 @@ static int qcom_ipcc_probe(struct platform_device *pdev)
> > if (IS_ERR(ipcc->base))
> > return PTR_ERR(ipcc->base);
> >
> > + /*
> > + * It is possible that boot firmware is using the same IPCC instance
> > + * as of the HLOS and it has kept CLEAR_ON_RECV_RD set which basically
> > + * means Interrupt pending registers are cleared when RECV_ID is read.
> > + * The register automatically updates to the next pending interrupt/client
> > + * status based on priority.
> > + */
> > + config_value = readl(ipcc->base + IPCC_REG_CONFIG);
> > + if (config_value & IPCC_CLEAR_ON_RECV_RD) {
>
> Can't you just clear this bit always?
We can do, but i wanted to be explicit here that something been done
from bootloader which Linux would need to clear.
I see this patch is merged in mainline.
-Mukesh
>
> - Mani
>
> --
> மணிவண்ணன் சதாசிவம்
