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Message-ID: <c1bac8c0-062a-72ed-e120-802965472191@loongson.cn>
Date: Sat, 24 Jun 2023 23:53:38 +0800
From: Sui Jingfeng <suijingfeng@...ngson.cn>
To: Lucas Stach <l.stach@...gutronix.de>,
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
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;
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");
--
Jingfeng
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