linux-kernel - Re: [PATCH v4 2/5] PCI: tegra194: Move dw_pcie_ep

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Message-ID: <20221114110820.GM3869@thinkpad>
Date:   Mon, 14 Nov 2022 16:38:20 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     vidyas@...dia.com
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        kw@...ux.com, robh@...nel.org, lpieralisi@...nel.org,
        bhelgaas@...gle.com
Subject: Re: [PATCH v4 2/5] PCI: tegra194: Move dw_pcie_ep_linkup() to
 threaded IRQ handler

On Mon, Nov 14, 2022 at 04:37:00PM +0530, Manivannan Sadhasivam wrote:
> On Tue, Oct 25, 2022 at 08:20:58PM +0530, Manivannan Sadhasivam wrote:
> > dw_pcie_ep_linkup() may take more time to execute depending on the EPF
> > driver implementation. Calling this API in the hard IRQ handler is not
> > encouraged since the hard IRQ handlers are supposed to complete quickly.
> > 
> > So move the dw_pcie_ep_linkup() call to threaded IRQ handler.
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

Sorry for resending it (something messed up with my email client).

Vidya, can you please review this patch?

Thanks,
Mani

> > ---
> >  drivers/pci/controller/dwc/pcie-tegra194.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> > index 1b6b437823d2..a0d231b7a435 100644
> > --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> > +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> > @@ -287,6 +287,7 @@ struct tegra_pcie_dw {
> >  	struct gpio_desc *pex_refclk_sel_gpiod;
> >  	unsigned int pex_rst_irq;
> >  	int ep_state;
> > +	long link_status;
> >  };
> >  
> >  static inline struct tegra_pcie_dw *to_tegra_pcie(struct dw_pcie *pci)
> > @@ -450,9 +451,13 @@ static void pex_ep_event_hot_rst_done(struct tegra_pcie_dw *pcie)
> >  static irqreturn_t tegra_pcie_ep_irq_thread(int irq, void *arg)
> >  {
> >  	struct tegra_pcie_dw *pcie = arg;
> > +	struct dw_pcie_ep *ep = &pcie->pci.ep;
> >  	struct dw_pcie *pci = &pcie->pci;
> >  	u32 val, speed;
> >  
> > +	if (test_and_clear_bit(0, &pcie->link_status))
> > +		dw_pcie_ep_linkup(ep);
> > +
> >  	speed = dw_pcie_readw_dbi(pci, pcie->pcie_cap_base + PCI_EXP_LNKSTA) &
> >  		PCI_EXP_LNKSTA_CLS;
> >  	clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
> > @@ -499,7 +504,6 @@ static irqreturn_t tegra_pcie_ep_irq_thread(int irq, void *arg)
> >  static irqreturn_t tegra_pcie_ep_hard_irq(int irq, void *arg)
> >  {
> >  	struct tegra_pcie_dw *pcie = arg;
> > -	struct dw_pcie_ep *ep = &pcie->pci.ep;
> >  	int spurious = 1;
> >  	u32 status_l0, status_l1, link_status;
> >  
> > @@ -515,7 +519,8 @@ static irqreturn_t tegra_pcie_ep_hard_irq(int irq, void *arg)
> >  			link_status = appl_readl(pcie, APPL_LINK_STATUS);
> >  			if (link_status & APPL_LINK_STATUS_RDLH_LINK_UP) {
> >  				dev_dbg(pcie->dev, "Link is up with Host\n");
> > -				dw_pcie_ep_linkup(ep);
> > +				set_bit(0, &pcie->link_status);
> > +				return IRQ_WAKE_THREAD;
> >  			}
> >  		}
> >  
> > -- 
> > 2.25.1
> > 
> 
> -- 
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