RE: [PATCH v3] irqchip: xilinx: Add support for multiple instances

[Mubin Usman Sayyed <MUBINUSM@xilinx.com>]

Hi Thomas,

Thanks for the review. Please see my inline replies.

> -----Original Message-----
> From: Thomas Gleixner <tglx@linutronix.de>
> Sent: Thursday, February 13, 2020 5:31 PM
> To: Mubin Usman Sayyed <MUBINUSM@xilinx.com>;
> jason@lakedaemon.net; maz@kernel.org; Michal Simek
> <michals@xilinx.com>; linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org; Siva Durga Prasad Paladugu
> <sivadur@xilinx.com>; Anirudha Sarangi <anirudh@xilinx.com>; Mubin
> Usman Sayyed <MUBINUSM@xilinx.com>
> Subject: Re: [PATCH v3] irqchip: xilinx: Add support for multiple instances
> 
> Mubin,
> 
> Mubin Usman Sayyed <mubin.usman.sayyed@xilinx.com> writes:
> 
> > From: Mubin Sayyed <mubin.usman.sayyed@xilinx.com>
> >
> > This patch adds support for multiple instances of
> 
> git grep 'This patch' Documentation/process/submitting-patches.rst
[Mubin]: I will re-phrase it in next version.
> 
> > xilinx interrupt controller. Below configurations are supported by
> > driver,
> >
> > - peripheral->xilinx-intc->xilinx-intc->gic
> > - peripheral->xilinx-intc->xilinx-intc
> 
> This is really not much of an explanation.
[Mubin]: Will elaborate in next version
> 
> > Signed-off-by: Anirudha Sarangi <anirudha.sarangi@xilinx.com>
> > Signed-off-by: Mubin Sayyed <mubin.usman.sayyed@xilinx.com>
> 
> This Signed-off-by chain is incorrect. See chapter 11 and 12 in the same
> document.
[Mubin]:  Sure, I will check and fix it. I ran checkpatch, it didn't reported errors/warning related to that. 
> 
> > @@ -38,29 +38,32 @@ struct xintc_irq_chip {
> >  	void		__iomem *base;
> >  	struct		irq_domain *root_domain;
> >  	u32		intr_mask;
> > +	struct		irq_chip *intc_dev;
> > +	u32		nr_irq;
> >  };
> >
> > -static struct xintc_irq_chip *xintc_irqc;
> > +static struct xintc_irq_chip *primary_intc;
> >
> > -static void xintc_write(int reg, u32 data)
> > +static void xintc_write(struct xintc_irq_chip *irqc, int reg, u32
> > +data)
> >  {
> >  	if (static_branch_unlikely(&xintc_is_be))
> > -		iowrite32be(data, xintc_irqc->base + reg);
> > +		iowrite32be(data, irqc->base + reg);
> >  	else
> > -		iowrite32(data, xintc_irqc->base + reg);
> > +		iowrite32(data, irqc->base + reg);
> >  }
> >
> > -static unsigned int xintc_read(int reg)
> > +static u32 xintc_read(struct xintc_irq_chip *irqc, int reg)
> >  {
> >  	if (static_branch_unlikely(&xintc_is_be))
> > -		return ioread32be(xintc_irqc->base + reg);
> > +		return ioread32be(irqc->base + reg);
> >  	else
> > -		return ioread32(xintc_irqc->base + reg);
> > +		return ioread32(irqc->base + reg);
> >  }
> >
> >  static void intc_enable_or_unmask(struct irq_data *d)  {
> > -	unsigned long mask = 1 << d->hwirq;
> > +	unsigned long mask = BIT(d->hwirq);
> > +	struct xintc_irq_chip *irqc = irq_data_get_irq_chip_data(d);
> 
> Please order your local variables in reverse fir tree order:
> 
> 	struct xintc_irq_chip *irqc = irq_data_get_irq_chip_data(d);
>         unsigned long mask = BIT(d->hwirq);
> 
> which is the preferred coding style in this subsystem and way simpler to
> read.
[Mubin]: I will fix  all such  instances in next version
> 
> >  static void intc_mask_ack(struct irq_data *d)  {
> > -	unsigned long mask = 1 << d->hwirq;
> > +	unsigned long mask = BIT(d->hwirq);
> > +	struct xintc_irq_chip *irqc = irq_data_get_irq_chip_data(d);
> 
> Ditto.
> 
> >  	pr_debug("irq-xilinx: disable_and_ack: %ld\n", d->hwirq);
> > -	xintc_write(CIE, mask);
> > -	xintc_write(IAR, mask);
> > +	xintc_write(irqc, CIE, mask);
> > +	xintc_write(irqc, IAR, mask);
> >  }
> > +static unsigned int xintc_get_irq_local(struct xintc_irq_chip *irqc)
> > +{
> > +	u32 hwirq;
> > +	unsigned int irq = 0;
> 
> Same.
> 
> > +	hwirq = xintc_read(irqc, IVR);
> > +	if (hwirq != -1U)
> > +		irq = irq_find_mapping(irqc->root_domain, hwirq);
> > +
> > +	pr_debug("irq-xilinx: hwirq=%d, irq=%d\n", hwirq, irq);
> 
> Are these pr_debugs all over the please really required? I can understand
> that you use them for development, but are they useful once the stuff
> works?
[Mubin]  They might be useful to debug interrupt issues. Do you want me to remove them?
> 
> > +	return irq;
> > +}
> > +
> >  unsigned int xintc_get_irq(void)
> >  {
> > -	unsigned int hwirq, irq = -1;
> > +	u32 hwirq;
> > +	unsigned int irq = -1;
> 
> See above.
> 
> > -	hwirq = xintc_read(IVR);
> > +	hwirq = xintc_read(primary_intc, IVR);
> >  	if (hwirq != -1U)
> > -		irq = irq_find_mapping(xintc_irqc->root_domain, hwirq);
> > +		irq = irq_find_mapping(primary_intc->root_domain, hwirq);
> >
> >  	pr_debug("irq-xilinx: hwirq=%d, irq=%d\n", hwirq, irq);
> >
> > @@ -138,12 +164,14 @@ static const struct irq_domain_ops
> > xintc_irq_domain_ops = {  static void xil_intc_irq_handler(struct
> > irq_desc *desc)  {
> >  	struct irq_chip *chip = irq_desc_get_chip(desc);
> > +	struct xintc_irq_chip *irqc =
> > +		irq_data_get_irq_handler_data(&desc->irq_data);
> 
> Please avoid these ugly line breaks and put the initialization of the variable in
> to the code below the declaration.
[Mubin]: Will do in next version
> 
> >  	/* Turn on the Master Enable. */
> > -	xintc_write(MER, MER_HIE | MER_ME);
> > -	if (!(xintc_read(MER) & (MER_HIE | MER_ME))) {
> > +	xintc_write(irqc, MER, MER_HIE | MER_ME);
> > +	if (!(xintc_read(irqc, MER) & (MER_HIE | MER_ME))) {
> >  		static_branch_enable(&xintc_is_be);
> 
> I see it's existing logic, but this lacks a comment how it's determined that
> xintc is big endian. Looks like some weird "write works?"
> probing. Why?
> 
> > +	xintc_write(irqc, MER, MER_HIE | MER_ME);
> 
> So this writes MER_HIE | MER_ME into MER
> 
> > +	if (!(xintc_read(irqc, MER) & (MER_HIE | MER_ME))) {
> 
> but this checks just whether ONE of the bits is set. Shouldn't it check for MER
> == (MER_HIE | MER_ME), i.e. read back what was written?

[Mubin]:  Agreed, will fix it in v4.

Thanks,
Mubin
> 
> Thanks,
> 
>         tglx