linux-kernel - Re: [PATCH v5 2/6] PCI: uniphier: Add misc interrupt handler to invoke PME and AER

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Message-ID: <2a2bb86a4afcbd60d3399953b5af8b69@kernel.org>
Date:   Tue, 30 Jun 2020 14:23:24 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Rob Herring <robh+dt@...nel.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Masami Hiramatsu <masami.hiramatsu@...aro.org>,
        Jassi Brar <jaswinder.singh@...aro.org>
Subject: Re: [PATCH v5 2/6] PCI: uniphier: Add misc interrupt handler to
 invoke PME and AER

On 2020-06-29 10:49, Kunihiko Hayashi wrote:
> Hi Marc,
> 
> On 2020/06/27 18:48, Marc Zyngier wrote:
>> On Thu, 18 Jun 2020 09:38:09 +0100,
>> Kunihiko Hayashi <hayashi.kunihiko@...ionext.com> wrote:
>>> 
>>> The misc interrupts consisting of PME, AER, and Link event, is 
>>> handled
>>> by INTx handler, however, these interrupts should be also handled by
>>> MSI handler.
>>> 
>>> This adds the function uniphier_pcie_misc_isr() that handles misc
>>> interrupts, which is called from both INTx and MSI handlers.
>>> This function detects PME and AER interrupts with the status 
>>> register,
>>> and invoke PME and AER drivers related to MSI.
>>> 
>>> And this sets the mask for misc interrupts from INTx if MSI is 
>>> enabled
>>> and sets the mask for misc interrupts from MSI if MSI is disabled.
>>> 
>>> Cc: Marc Zyngier <maz@...nel.org>
>>> Cc: Jingoo Han <jingoohan1@...il.com>
>>> Cc: Gustavo Pimentel <gustavo.pimentel@...opsys.com>
>>> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
>>> ---
>>>   drivers/pci/controller/dwc/pcie-uniphier.c | 57 
>>> ++++++++++++++++++++++++------
>>>   1 file changed, 46 insertions(+), 11 deletions(-)
>>> 
>>> diff --git a/drivers/pci/controller/dwc/pcie-uniphier.c 
>>> b/drivers/pci/controller/dwc/pcie-uniphier.c
>>> index a5401a0..5ce2479 100644
>>> --- a/drivers/pci/controller/dwc/pcie-uniphier.c
>>> +++ b/drivers/pci/controller/dwc/pcie-uniphier.c
>>> @@ -44,7 +44,9 @@
>>>   #define PCL_SYS_AUX_PWR_DET		BIT(8)
>>>     #define PCL_RCV_INT			0x8108
>>> +#define PCL_RCV_INT_ALL_INT_MASK	GENMASK(28, 25)
>>>   #define PCL_RCV_INT_ALL_ENABLE		GENMASK(20, 17)
>>> +#define PCL_RCV_INT_ALL_MSI_MASK	GENMASK(12, 9)
>>>   #define PCL_CFG_BW_MGT_STATUS		BIT(4)
>>>   #define PCL_CFG_LINK_AUTO_BW_STATUS	BIT(3)
>>>   #define PCL_CFG_AER_RC_ERR_MSI_STATUS	BIT(2)
>>> @@ -167,7 +169,15 @@ static void uniphier_pcie_stop_link(struct 
>>> dw_pcie *pci)
>>>     static void uniphier_pcie_irq_enable(struct uniphier_pcie_priv 
>>> *priv)
>>>   {
>>> -	writel(PCL_RCV_INT_ALL_ENABLE, priv->base + PCL_RCV_INT);
>>> +	u32 val;
>>> +
>>> +	val = PCL_RCV_INT_ALL_ENABLE;
>>> +	if (pci_msi_enabled())
>>> +		val |= PCL_RCV_INT_ALL_INT_MASK;
>>> +	else
>>> +		val |= PCL_RCV_INT_ALL_MSI_MASK;
>> 
>> Does this affect endpoints? Or just the RC itself?
> 
> These interrupts are asserted by RC itself, so this part affects only 
> RC.
> 
>>> +
>>> +	writel(val, priv->base + PCL_RCV_INT);
>>>   	writel(PCL_RCV_INTX_ALL_ENABLE, priv->base + PCL_RCV_INTX);
>>>   }
>>>   @@ -231,32 +241,56 @@ static const struct irq_domain_ops 
>>> uniphier_intx_domain_ops = {
>>>   	.map = uniphier_pcie_intx_map,
>>>   };
>>>   -static void uniphier_pcie_irq_handler(struct irq_desc *desc)
>>> +static void uniphier_pcie_misc_isr(struct pcie_port *pp, bool 
>>> is_msi)
>>>   {
>>> -	struct pcie_port *pp = irq_desc_get_handler_data(desc);
>>>   	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>>>   	struct uniphier_pcie_priv *priv = to_uniphier_pcie(pci);
>>> -	struct irq_chip *chip = irq_desc_get_chip(desc);
>>> -	unsigned long reg;
>>> -	u32 val, bit, virq;
>>> +	u32 val, virq;
>>>   -	/* INT for debug */
>>>   	val = readl(priv->base + PCL_RCV_INT);
>>>     	if (val & PCL_CFG_BW_MGT_STATUS)
>>>   		dev_dbg(pci->dev, "Link Bandwidth Management Event\n");
>>> +
>>>   	if (val & PCL_CFG_LINK_AUTO_BW_STATUS)
>>>   		dev_dbg(pci->dev, "Link Autonomous Bandwidth Event\n");
>>> -	if (val & PCL_CFG_AER_RC_ERR_MSI_STATUS)
>>> -		dev_dbg(pci->dev, "Root Error\n");
>>> -	if (val & PCL_CFG_PME_MSI_STATUS)
>>> -		dev_dbg(pci->dev, "PME Interrupt\n");
>>> +
>>> +	if (is_msi) {
>>> +		if (val & PCL_CFG_AER_RC_ERR_MSI_STATUS)
>>> +			dev_dbg(pci->dev, "Root Error Status\n");
>>> +
>>> +		if (val & PCL_CFG_PME_MSI_STATUS)
>>> +			dev_dbg(pci->dev, "PME Interrupt\n");
>>> +
>>> +		if (val & (PCL_CFG_AER_RC_ERR_MSI_STATUS |
>>> +			   PCL_CFG_PME_MSI_STATUS)) {
>>> +			virq = irq_linear_revmap(pp->irq_domain, 0);
>>> +			generic_handle_irq(virq);
>>> +		}
>>> +	}
>> 
>> Please have two handlers: one for interrupts that are from the RC,
>> another for interrupts coming from the endpoints.
> I assume that this handler treats interrupts from the RC only and
> this is set on the member ".msi_host_isr" added in the patch 1/6.
> I think that the handler for interrupts coming from endpoints should be
> treated as a normal case (after calling .msi_host_isr in
> dw_handle_msi_irq()).

It looks pretty odd that you end-up dealing with both from the
same "parent" interrupt. I guess this is in keeping with the
rest of the DW PCIe hacks... :-/

It is for Lorenzo to make up his mind about this anyway.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...