Hi,
On 07/12/18 3:15 PM, Marc Zyngier wrote:
> On 07/12/2018 08:12, Kishon Vijay Abraham I wrote:
>> Hi Marc,
>>
>> On 04/12/18 7:15 PM, Marc Zyngier wrote:
>>> On Tue, 4 Dec 2018 15:50:32 +0530
>>> Kishon Vijay Abraham I <kishon@xxxxxx> wrote:
>>>
>>>> Hi,
>>>>
>>>> On 14/11/18 4:27 AM, Marc Zyngier wrote:
>>>>> The write to the status register is really an ACK for the HW,
>>>>> and should be treated as such by the driver. Let's move it to the
>>>>> irq_ack callback, which will prevent people from moving it around
>>>>> in order to paper over other bugs.
>>>>>
>>>>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>>>>> ---
>>>>> drivers/pci/controller/dwc/pcie-designware-host.c | 13 +++++++------
>>>>> 1 file changed, 7 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
>>>>> index 0a76948ed49e..f06e67c60593 100644
>>>>> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
>>>>> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
>>>>> @@ -99,9 +99,6 @@ irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
>>>>> (i * MAX_MSI_IRQS_PER_CTRL) +
>>>>> pos);
>>>>> generic_handle_irq(irq);
>>>>> - dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_STATUS +
>>>>> - (i * MSI_REG_CTRL_BLOCK_SIZE),
>>>>> - 4, 1 << pos);
>>>>> pos++;
>>>>> }
>>>>> }
>>>>> @@ -200,14 +197,18 @@ static void dw_pci_bottom_unmask(struct irq_data *data)
>>>>>
>>>>> static void dw_pci_bottom_ack(struct irq_data *d)
>>>>> {
>>>>> - struct msi_desc *msi = irq_data_get_msi_desc(d);
>>>>> - struct pcie_port *pp;
>>>>> + struct pcie_port *pp = irq_data_get_irq_chip_data(d);
>>>>> + unsigned int res, bit, ctrl;
>>>>> unsigned long flags;
>>>>>
>>>>> - pp = msi_desc_to_pci_sysdata(msi);
>>>>> + ctrl = d->hwirq / MAX_MSI_IRQS_PER_CTRL;
>>>>> + res = ctrl * MSI_REG_CTRL_BLOCK_SIZE;
>>>>> + bit = d->hwirq % MAX_MSI_IRQS_PER_CTRL;
>>>>>
>>>>> raw_spin_lock_irqsave(&pp->lock, flags);
>>>>>
>>>>> + dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_STATUS + res, 4, 1 << bit);
>>>>
>>>> This register should be written only if msi_irq_ack callback is not populated
>>>> similar to other dw_pci_bottom_*() functions.
>>>
>>> Why? This was so far unconditionally written, and my understanding is
>>> that without this write, no further MSI can be delivered.
>>
>> Not all platforms invoke dw_handle_msi_irq() for handling MSI irq.
>>
>> Platforms that doesn't use the MSI functionality of Designware makes use of the
>> various callbacks like msi_irq_ack, msi_host_init etc., Keystone has MSI
>> controller in the Keystone wrapper, AM654 uses GIC ITS etc.,
>>
>> The platforms that doesn't use MSI functionality of Designware doesn't have to
>> write to Designware's MSI configuration registers.
>
> Let's be clear: a platform that doesn't use the DW MSI functionality
> should never get anywhere this code. If they do, then that's a terrible
> bug, and it should be fixed by making the TI stuff standalone instead of
> calling into the internals.
That makes sense to me. We can start by removing msi_set_irq, msi_clear_irq and
msi_irq_ack callbacks from dw_pcie_host_ops.
This functionality can be added directly in keystone driver.
>
> Frankly, this whole thing should be marked as BROKEN until it is sorted
> out for good.
Maybe remove those callbacks and make only Keystone broken?
Thanks
Kishon
