[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Oliver Neukum]

Am Mittwoch, den 14.03.2018, 14:31 +0100 schrieb Richard Leitner:
> Hi Oliver,
> thank you for your feedback!
> 
> On 03/14/2018 01:17 PM, Oliver Neukum wrote:
> > Am Mittwoch, den 14.03.2018, 11:29 +0100 schrieb Richard Leitner:
> > > From: Richard Leitner <richard.leitner@skidata.com>
> > > 
> > > Replace the hardcoded PCI vendor ID of Netlogic with a definition in
> > > pci_ids.h
> > 
> > Hi,
> > 
> > in general, why?
> > Does this patch generate any benefit for any developer
> > reading the source? I don't see it. Does it cause an
> > issue for anybody who has a log file with the nummerical
> > ID and needs to grep for it? Yes it does.
> 
> I'll send a v2 where I also use this definition in 
> arch/mips/netlogic/xlp/ instead of PCI_VENDOR_NETLOGIC from
> arch/mips/include/asm/netlogic/xlp-hal/iomap.h.
> 
> Therefore it will remove this definition from the iomap.h
> and move it to pci_ids.h
> 
> This will IMHO be a clear benefit as it removes a redundant
> definition.

Well, but it does not. Removing a redundant definition is a clear
benefit. But you are not removing a definition. You are introducing
a preprocessor constant. Why?
What is its benefit?

	Regards
		Oliver
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[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Richard Leitner]

On 03/15/2018 10:26 AM, Oliver Neukum wrote:
> Am Mittwoch, den 14.03.2018, 16:44 +0100 schrieb Richard Leitner:
>> On 03/14/2018 04:27 PM, Oliver Neukum wrote:
>>> Am Mittwoch, den 14.03.2018, 14:31 +0100 schrieb Richard Leitner:
>>>>
>>> Well, but it does not. Removing a redundant definition is a clear
>>> benefit. But you are not removing a definition. You are introducing
>>> a preprocessor constant. Why?
>>> What is its benefit?
>>
>> AFAIK pci_ids.h collects PCI vendor and device IDs in one single 
>> point. As the PCI vendor ID of Netlogic is used in multiple files
>> IMHO it would be a good idea to add it to pci_ids.h and furthermore
>> remove it from arch/mips/include/asm/netlogic/xlp-hal/iomap.h (where
>> it's currently defined).
>>
>> Or am I getting things wrong?
> 
> I think so, yes. We are giving names to constants as a form
> of comment or to change them at multiple places at once and
> consistently.
> 
> So
> 
> #define XYZ_NETDEV_RESET_RETRIES	2
> 
> makes clearly sense. So does
> 
> #define XYZ_MAGIC_VALUE1	0xab4e
> 
> because it tells you that you have a magic value.
> But you will never redefine a PCI vendor ID. In fact you
> must not. And if you have a comparison like
> 
> dev->vID == 0x1234
> 
> if you change this to
> 
> dev->vID == SOME_VENDOR_ID
> 
> what good does this to you? You already knew it was a vendor ID.
> Now you can name it at a glance. So what? If you have a device
> you will have to check whether you have some OEM version. You
> will always go and check the raw number. And if you have a log
> and need to check whether the check will be true, you will have
> a number.
> Using a constant there is nothing but trouble. Yet one more grep.

Thank you for that explanation. But IMHO it was clearer with a
human-readable name in such comparisons...

For example in the following I see at the first glance which
device from which vendor is affected and I don't need any
additional comments or ID databases...
       if (pdev->vendor == PCI_VENDOR_ID_TI &&
           pdev->device == PCI_DEVICE_ID_TI_TUSB73X0)

...but if that's not the preferred way of doing things I'm
perfectly fine with that.

Furthermore to me it sounds you are saying that the complete
pci_ids.h should be thrown over-board?!?

regards;richard.l
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[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Oliver Neukum]

Am Mittwoch, den 14.03.2018, 16:44 +0100 schrieb Richard Leitner:
> On 03/14/2018 04:27 PM, Oliver Neukum wrote:
> > Am Mittwoch, den 14.03.2018, 14:31 +0100 schrieb Richard Leitner:
> > > 
> > Well, but it does not. Removing a redundant definition is a clear
> > benefit. But you are not removing a definition. You are introducing
> > a preprocessor constant. Why?
> > What is its benefit?
> 
> AFAIK pci_ids.h collects PCI vendor and device IDs in one single 
> point. As the PCI vendor ID of Netlogic is used in multiple files
> IMHO it would be a good idea to add it to pci_ids.h and furthermore
> remove it from arch/mips/include/asm/netlogic/xlp-hal/iomap.h (where
> it's currently defined).
> 
> Or am I getting things wrong?

I think so, yes. We are giving names to constants as a form
of comment or to change them at multiple places at once and
consistently.

So

#define XYZ_NETDEV_RESET_RETRIES	2

makes clearly sense. So does

#define XYZ_MAGIC_VALUE1	0xab4e

because it tells you that you have a magic value.
But you will never redefine a PCI vendor ID. In fact you
must not. And if you have a comparison like

dev->vID == 0x1234

if you change this to

dev->vID == SOME_VENDOR_ID

what good does this to you? You already knew it was a vendor ID.
Now you can name it at a glance. So what? If you have a device
you will have to check whether you have some OEM version. You
will always go and check the raw number. And if you have a log
and need to check whether the check will be true, you will have
a number.
Using a constant there is nothing but trouble. Yet one more grep.

	Regards
		Oliver
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[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Richard Leitner]

On 03/14/2018 04:27 PM, Oliver Neukum wrote:
> Am Mittwoch, den 14.03.2018, 14:31 +0100 schrieb Richard Leitner:
>> Hi Oliver,
>> thank you for your feedback!
>>
>> On 03/14/2018 01:17 PM, Oliver Neukum wrote:
>>> Am Mittwoch, den 14.03.2018, 11:29 +0100 schrieb Richard Leitner:
>>>> From: Richard Leitner <richard.leitner@skidata.com>
>>>>
>>>> Replace the hardcoded PCI vendor ID of Netlogic with a definition in
>>>> pci_ids.h
>>>
>>> Hi,
>>>
>>> in general, why?
>>> Does this patch generate any benefit for any developer
>>> reading the source? I don't see it. Does it cause an
>>> issue for anybody who has a log file with the nummerical
>>> ID and needs to grep for it? Yes it does.
>>
>> I'll send a v2 where I also use this definition in 
>> arch/mips/netlogic/xlp/ instead of PCI_VENDOR_NETLOGIC from
>> arch/mips/include/asm/netlogic/xlp-hal/iomap.h.
>>
>> Therefore it will remove this definition from the iomap.h
>> and move it to pci_ids.h
>>
>> This will IMHO be a clear benefit as it removes a redundant
>> definition.
> 
> Well, but it does not. Removing a redundant definition is a clear
> benefit. But you are not removing a definition. You are introducing
> a preprocessor constant. Why?
> What is its benefit?

AFAIK pci_ids.h collects PCI vendor and device IDs in one single 
point. As the PCI vendor ID of Netlogic is used in multiple files
IMHO it would be a good idea to add it to pci_ids.h and furthermore
remove it from arch/mips/include/asm/netlogic/xlp-hal/iomap.h (where
it's currently defined).

Or am I getting things wrong?

regards;richard.l
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[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Richard Leitner]

Hi Oliver,
thank you for your feedback!

On 03/14/2018 01:17 PM, Oliver Neukum wrote:
> Am Mittwoch, den 14.03.2018, 11:29 +0100 schrieb Richard Leitner:
>> From: Richard Leitner <richard.leitner@skidata.com>
>>
>> Replace the hardcoded PCI vendor ID of Netlogic with a definition in
>> pci_ids.h
> 
> Hi,
> 
> in general, why?
> Does this patch generate any benefit for any developer
> reading the source? I don't see it. Does it cause an
> issue for anybody who has a log file with the nummerical
> ID and needs to grep for it? Yes it does.

I'll send a v2 where I also use this definition in 
arch/mips/netlogic/xlp/ instead of PCI_VENDOR_NETLOGIC from
arch/mips/include/asm/netlogic/xlp-hal/iomap.h.

Therefore it will remove this definition from the iomap.h
and move it to pci_ids.h

This will IMHO be a clear benefit as it removes a redundant
definition.

> 
> Where is the point of this patch?
> 
> 	Regards
> 		Oliver
> 

regards;Richard.L
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[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Oliver Neukum]

Am Mittwoch, den 14.03.2018, 11:29 +0100 schrieb Richard Leitner:
> From: Richard Leitner <richard.leitner@skidata.com>
> 
> Replace the hardcoded PCI vendor ID of Netlogic with a definition in
> pci_ids.h

Hi,

in general, why?
Does this patch generate any benefit for any developer
reading the source? I don't see it. Does it cause an
issue for anybody who has a log file with the nummerical
ID and needs to grep for it? Yes it does.

Where is the point of this patch?

	Regards
		Oliver
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[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Greg Kroah-Hartman]

On Wed, Mar 14, 2018 at 12:36:17PM +0100, Richard Leitner wrote:
> 
> On 03/14/2018 11:48 AM, Greg KH wrote:
> > On Wed, Mar 14, 2018 at 11:29:32AM +0100, Richard Leitner wrote:
> >> From: Richard Leitner <richard.leitner@skidata.com>
> >>
> >> Replace the hardcoded PCI vendor ID of Netlogic with a definition in
> >> pci_ids.h
> > 
> > Why?  It's only being used in one file, so it should not be in
> > pci_ids.h, right?
> 
> It's also used as PCI_VENDOR_NETLOGIC in arch/mips/netlogic/xlp/.
> 
> Should this be replaced with PCI_VENDOR_ID_NETLOGIC from pci_ids.h?

Yes, if you are going to add it to pci_ids.h, it had better be used by
multiple files, otherwise it does not belong in there.

thanks,

greg k-h
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[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Richard Leitner]

On 03/14/2018 11:48 AM, Greg KH wrote:
> On Wed, Mar 14, 2018 at 11:29:32AM +0100, Richard Leitner wrote:
>> From: Richard Leitner <richard.leitner@skidata.com>
>>
>> Replace the hardcoded PCI vendor ID of Netlogic with a definition in
>> pci_ids.h
> 
> Why?  It's only being used in one file, so it should not be in
> pci_ids.h, right?

It's also used as PCI_VENDOR_NETLOGIC in arch/mips/netlogic/xlp/.

Should this be replaced with PCI_VENDOR_ID_NETLOGIC from pci_ids.h?

> 
> thanks,
> 
> greg k-h
> 

thank you!

regards;Richard.L
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[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Greg Kroah-Hartman]

On Wed, Mar 14, 2018 at 11:29:32AM +0100, Richard Leitner wrote:
> From: Richard Leitner <richard.leitner@skidata.com>
> 
> Replace the hardcoded PCI vendor ID of Netlogic with a definition in
> pci_ids.h

Why?  It's only being used in one file, so it should not be in
pci_ids.h, right?

thanks,

greg k-h
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[2/3] usb: host: pci: introduce PCI vendor ID for Netlogic

[Richard Leitner]

From: Richard Leitner <richard.leitner@skidata.com>

Replace the hardcoded PCI vendor ID of Netlogic with a definition in
pci_ids.h

Signed-off-by: Richard Leitner <richard.leitner@skidata.com>
---
 drivers/usb/host/pci-quirks.c | 2 +-
 include/linux/pci_ids.h       | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
index 4f4a9f36a68e..39d163729b89 100644
--- a/drivers/usb/host/pci-quirks.c
+++ b/drivers/usb/host/pci-quirks.c
@@ -1243,7 +1243,7 @@ static void quirk_usb_early_handoff(struct pci_dev *pdev)
 	/* Skip Netlogic mips SoC's internal PCI USB controller.
 	 * This device does not need/support EHCI/OHCI handoff
 	 */
-	if (pdev->vendor == 0x184e)	/* vendor Netlogic */
+	if (pdev->vendor == PCI_VENDOR_ID_NETLOGIC)
 		return;
 	if (pdev->class != PCI_CLASS_SERIAL_USB_UHCI &&
 			pdev->class != PCI_CLASS_SERIAL_USB_OHCI &&
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index e8d1af82a688..d23a97868dee 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -3067,4 +3067,6 @@
 
 #define PCI_VENDOR_ID_OCZ		0x1b85
 
+#define PCI_VENDOR_ID_NETLOGIC		0x184e
+
 #endif /* _LINUX_PCI_IDS_H */