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Message-ID: <3927bb24f1f3480bf2d25a9a0f608aec9e58240d.camel@pengutronix.de>
Date: Mon, 26 Jun 2023 12:57:37 +0200
From: Lucas Stach <l.stach@...gutronix.de>
To: Sui Jingfeng <suijingfeng@...ngson.cn>,
Sui Jingfeng <18949883232@....com>,
Russell King <linux+etnaviv@...linux.org.uk>,
Christian Gmeiner <christian.gmeiner@...il.com>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Philipp Zabel <p.zabel@...gutronix.de>,
linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
etnaviv@...ts.freedesktop.org
Subject: Re: [PATCH v10 01/11] drm/etnaviv: Add a dedicated function to
register an irq handler
Am Samstag, dem 24.06.2023 um 23:53 +0800 schrieb Sui Jingfeng:
> Hi,
>
> On 2023/6/21 18:16, Lucas Stach wrote:
> > Am Mittwoch, dem 21.06.2023 um 17:20 +0800 schrieb Sui Jingfeng:
> > > Hi,
> > >
> > > On 2023/6/21 17:07, Lucas Stach wrote:
> > > > Am Dienstag, dem 20.06.2023 um 17:47 +0800 schrieb Sui Jingfeng:
> > > > > From: Sui Jingfeng <suijingfeng@...ngson.cn>
> > > > >
> > > > > Because getting IRQ from a device is platform-dependent, PCI devices have
> > > > > different methods for getting an IRQ. This patch is a preparation to extend
> > > > > this driver for supporting the PCI devices.
> > > > >
> > > > > Cc: Lucas Stach <l.stach@...gutronix.de>
> > > > > Cc: Christian Gmeiner <christian.gmeiner@...il.com>
> > > > > Cc: Philipp Zabel <p.zabel@...gutronix.de>
> > > > > Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> > > > > Cc: Daniel Vetter <daniel@...ll.ch>
> > > > > Signed-off-by: Sui Jingfeng <suijingfeng@...ngson.cn>
> > > > > ---
> > > > > drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 32 +++++++++++++++++++--------
> > > > > 1 file changed, 23 insertions(+), 9 deletions(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> > > > > index de8c9894967c..a03e81337d8f 100644
> > > > > --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> > > > > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> > > > > @@ -1817,6 +1817,27 @@ static const struct of_device_id etnaviv_gpu_match[] = {
> > > > > };
> > > > > MODULE_DEVICE_TABLE(of, etnaviv_gpu_match);
> > > > >
> > > > > +static int etnaviv_gpu_register_irq(struct etnaviv_gpu *gpu, int irq)
> > > > > +{
> > > > > + struct device *dev = gpu->dev;
> > > > > + int err;
> > > > > +
> > > > > + if (irq < 0)
> > > > > + return irq;
> > > > > +
> > > > > + err = devm_request_irq(dev, irq, irq_handler, 0, dev_name(dev), gpu);
> > > > > + if (err) {
> > > > > + dev_err(dev, "failed to request irq %u: %d\n", irq, err);
> > > > > + return err;
> > > > > + }
> > > > > +
> > > > > + gpu->irq = irq;
> > > > > +
> > > > > + dev_info(dev, "irq(%d) handler registered\n", irq);
> > > > There is no reason to put this into the kernel log.
> > > I want to see the IRQ of the device when debugging,
> > >
> > > etnaviv actually print very less.
> > >
> > > This serve as a minimal signal to us the etnaviv_gpu_register_irq()
> > > function is successful at driver load time.
> > >
> > And debugging is a very different use-case than normal operation. If
> > it's needed at all, downgrade this to dev_dbg. This isn't interesting
> > information for a ordinary user of a system.
> >
> > > > It's no different
> > > > than other resources to the driver and we don't log each one of those
> > > > either.
> > > >
> > > > In fact I don't see any reason for this change in the first place.
> > > > Effectively you are moving a single function call into a new function,
> > > > which doesn't seem like an improvement.
> > > This is to make the patch easy to review, each patch is only introduce a
> > > small function,
> > >
> > What I'm saying is that I don't see the need to introduce this function
> > at all. All you need to do is move platform_get_irq out into the
> > platform device code path. The devm_request_irq can stay where it is,
> > as the only difference between platform and PCI device is how the irq
> > number is retrieved from the platform.
>
> Yes, you are right. I understand what are asking, but my point is:
>
>
> This patch is paving the way for us to introduce the PCI device driver.
>
> All of the patches before the patch
> v10-0006-drm-etnaviv-Add-driver-support-for-the-PCI-devic.patch
>
> are actually doing the preparation.
>
>
> Look at the patch 0006, I achieve the goal by 128 insertions and 7
> deletions.
>
> while the only 7 deletions are actually for code shading(convert the
> static function to global function).
>
> There is No large area diff and NO distortion.
>
> The goal is adding a PCI device driver on the top of what we already have.
>
>
> Before the cleanup, the etnaviv_gpu_platform_probe() function is just
> like is a *glue*.
>
> Originally, it integrate a lot of irrelevant part together.
>
>
> 1. Mapping MMIO registers make it platform-dependent;
>
> 2. Calling platform_get_irq(pdev, 0) make it platform-dependent;
>
I get that and I'm fine with moving this out of this function. But
that's not what you are actually doing in this patch. You are moving
devm_request_irq out of this function, which isn't necessary, since the
request IRQ is not platform dependent. It's the retrieval of the IRQ
number to request (platform_get_irq/pdev->irq) which is platform
dependent.
Regards,
Lucas
> 3. Getting Clocks by calling devm_clk_get() make it platform-dependent;
>
> 4. Calling component_add() make it subsytem and framework-dependent;
>
>
> All of above list item is deny us to introduce the PCI device driver
> wrapper.
>
> It(sub-functional code) is not relevant to each other.
>
> Hence the first five patch is actually do the clean,
>
> for the clarify(and tidy and good looking) of the patch 6.
>
>
> I will drop the printing, but keep the cleanup function there,
>
> Is this acceptable?
>
>
> > Regards,
> > Lucas
> >
> > > which is paving the way for we introducing the PCI device driver.
> > >
> > > Otherwise when we introducing the PCI device driver, the patch is looks
> > > ugly,
> > >
> > > It is difficult to review.
> > >
> > > > Regards,
> > > > Lucas
> > > >
> > > > > +
> > > > > + return 0;
> > > > > +}
> > > > > +
> > > > > static int etnaviv_gpu_platform_probe(struct platform_device *pdev)
> > > > > {
> > > > > struct device *dev = &pdev->dev;
> > > > > @@ -1837,16 +1858,9 @@ static int etnaviv_gpu_platform_probe(struct platform_device *pdev)
> > > > > return PTR_ERR(gpu->mmio);
> > > > >
> > > > > /* Get Interrupt: */
> > > > > - gpu->irq = platform_get_irq(pdev, 0);
> > > > > - if (gpu->irq < 0)
> > > > > - return gpu->irq;
> > > > > -
> > > > > - err = devm_request_irq(&pdev->dev, gpu->irq, irq_handler, 0,
> > > > > - dev_name(gpu->dev), gpu);
> > > > > - if (err) {
> > > > > - dev_err(dev, "failed to request IRQ%u: %d\n", gpu->irq, err);
> > > > > + err = etnaviv_gpu_register_irq(gpu, platform_get_irq(pdev, 0));
> > > > > + if (err)
> > > > > return err;
> > > > > - }
> > > > >
> > > > > /* Get Clocks: */
> > > > > gpu->clk_reg = devm_clk_get_optional(&pdev->dev, "reg");
>
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