netdev - Re: [net-next v1] net: wwan: t7xx: Parameterize data plane RX BAT and FAG count

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Message-Id: <20250516084320.66998caf@kernel.org>
Date: Tue, 20 May 2025 10:59:34 +0800
From: Jinjian Song <jinjian.song@...ocom.com>
To: kuba@...nel.org
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Subject: Re: [net-next v1] net: wwan: t7xx: Parameterize data plane RX BAT and FAG count

>On Fri, 16 May 2025 11:46:57 +0800 Jinjian Song wrote:
>> >Module parameters are discouraged, they are pretty poor as an API since
>> >they apply to all devices in the system. Can you describe what "frg"
>> >and "bat" are ? One of the existing APIs likely covers them.
>> >Please also describe the scope (are they per netdev or some sort of
>> >device level params)?  
>> 
>> MTK t7xx data plane hardware use BAT (Buffer Address Table) and FRG (Fragment) BAT
>> to describle and manager RX buffer, these buffers will apply for a fixed size after
>> the driver probe, and accompany the life cycle of the driver.
>> 
>> On some platforms, especially those that use swiotlb to manager buffers, without
>> changing the buffer pool provided by swiotlb, it's needed to adjust the buffers
>> used by the driver to meet the requirements.
>> So parameterize these buffers applicable to the MTK t7xx driver to facilitate
>> different platforms to work with different configurations. 
>
>Have you looked at
>https://docs.kernel.org/networking/ethtool-netlink.html#rings-set 
>?
>

Hi Jakub,
  Thanks, I've just learned this content.
  I think ETHTOOL_STRINGPARAM is a good summary of the ring parameters and can
be referred to and applied to WWAN. However, it seemes that this can't be configured
when the driver is loaded and requires an application through ioctrl. In addition,
directly using this parameter can't well correspond to the multiple buffer representing
BAT in the t7xx driver.

  If it's not feasible to directly add parameters for configuring this RX buffer(BAT/FAG) to 
the mtk_t7xx driver, would it be allowed to add aparameter for a default configuration 
ratio (1/2, 1/4)? Or is it not recommended to use driver parameters for mtk_t7xx driver.

Thanks,
Best Regards.