linux-kernel - Re: [PATCH] usb: xhci: Add module param for compliance quirk checking

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Message-Id: <20241203003040.1518504-1-xiehongyu1@kylinos.cn>
Date: Tue,  3 Dec 2024 08:30:40 +0800
From: xiehongyu1@...inos.cn
To: gregkh@...uxfoundation.org
Cc: linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org,
	mathias.nyman@...el.com,
	xiehongyu1@...inos.cn
Subject: Re: [PATCH] usb: xhci: Add module param for compliance quirk checking

Hi Greg,

On 2024/12/2 14:38, Greg KH wrote:
> On Mon, Dec 02, 2024 at 11:18:55AM +0800, xiehongyu1@...inos.cn wrote:
>> From: Hongyu Xie <xiehongyu1@...inos.cn>
>>
>> In the old way, vendor name and product name need to be put in
>> xhci_compliance_mode_recovery_timer_quirk_check, it's not convenient.
>>
>> So add two module param for convenience.
>
> Please no.  Module parameters are from the 1990's, they do not scale or
> work well anymore, please never add them.
>
>>
>> usage: put xhci-hcd.compliance_vendor=[vendor name]
>> xhci-hcd.compliance_product=[product name] in cmdline.
>>
>> In Ubuntu you can use "dmidecode -t system" to get vendor name and
>> product name.
>>
>> Signed-off-by: Hongyu Xie <xiehongyu1@...inos.cn>
>> ---
>>  drivers/usb/host/xhci.c | 18 ++++++++++++++++--
>>  1 file changed, 16 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>> index 5ebde8cae4fc..2007c27bfaf4 100644
>> --- a/drivers/usb/host/xhci.c
>> +++ b/drivers/usb/host/xhci.c
>> @@ -39,6 +39,14 @@ static unsigned long long quirks;
>>  module_param(quirks, ullong, S_IRUGO);
>>  MODULE_PARM_DESC(quirks, "Bit flags for quirks to be enabled as default");
>>  
>> +static char *compliance_product;
>> +module_param(compliance_product, charp, 0644);
>> +MODULE_PARM_DESC(compliance_product, "Product name for compliance comparison");
>> +
>> +static char *compliance_vendor;
>> +module_param(compliance_vendor, charp, 0644);
>> +MODULE_PARM_DESC(compliance_vendor, "Vendor name for compliance comparison");
>
> Also, you have provided no documentation as to why these are needed at
> all, so that's not going to work :(
Engenieer from RENESA suggested to put vendor name and product name in
xhci_compliance_mode_recovery_timer_quirk_check for some buggy
motherboard that using uPD720201.
For oem(or odm), there might be multiple names for the same
motherboard(or same design). And put all the names in
xhci_compliance_mode_recovery_timer_quirk_check might not be a good
idea. So I figure using module_param can do the job. Anyway, Is there
better way to do this in kernel?
>
>
> thanks,
>
> greg k-h
>