Re: [PATCH V2 net-next 3/6] ethtool: add support to set/get rx buf len via ethtool

["huangguangbin (A)" <huangguangbin2@huawei.com>]

On 2021/9/25 7:14, Michal Kubecek wrote:
> On Fri, Sep 24, 2021 at 10:29:56PM +0800, Guangbin Huang wrote:
>> From: Hao Chen <chenhao288@hisilicon.com>
>>
>> Add support to set rx buf len via ethtool -G parameter and get
>> rx buf len via ethtool -g parameter.
>>
>> Signed-off-by: Hao Chen <chenhao288@hisilicon.com>
>> Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
>> ---
>>   Documentation/networking/ethtool-netlink.rst |  2 ++
>>   include/linux/ethtool.h                      | 18 ++++++++++++++++--
>>   include/uapi/linux/ethtool.h                 |  8 ++++++++
>>   include/uapi/linux/ethtool_netlink.h         |  1 +
>>   net/ethtool/netlink.h                        |  2 +-
>>   net/ethtool/rings.c                          | 17 ++++++++++++++++-
>>   6 files changed, 44 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
>> index a47b0255aaf9..9734b7c1e05d 100644
>> --- a/Documentation/networking/ethtool-netlink.rst
>> +++ b/Documentation/networking/ethtool-netlink.rst
>> @@ -841,6 +841,7 @@ Kernel response contents:
>>     ``ETHTOOL_A_RINGS_RX_MINI``           u32     size of RX mini ring
>>     ``ETHTOOL_A_RINGS_RX_JUMBO``          u32     size of RX jumbo ring
>>     ``ETHTOOL_A_RINGS_TX``                u32     size of TX ring
>> +  ``ETHTOOL_A_RINGS_RX_BUF_LEN``        u32     size of buffers on the ring
>>     ====================================  ======  ==========================
>>   
>>   
>> @@ -857,6 +858,7 @@ Request contents:
>>     ``ETHTOOL_A_RINGS_RX_MINI``           u32     size of RX mini ring
>>     ``ETHTOOL_A_RINGS_RX_JUMBO``          u32     size of RX jumbo ring
>>     ``ETHTOOL_A_RINGS_TX``                u32     size of TX ring
>> +  ``ETHTOOL_A_RINGS_RX_BUF_LEN``        u32     size of buffers on the ring
>>     ====================================  ======  ==========================
>>   
>>   Kernel checks that requested ring sizes do not exceed limits reported by
> 
> Would it make sense to let driver report also maximum supported value
> like it does for existing ring parameters (ring sizes)?
> 
> Michal
> 
We think it have no sense to report maximum supported value.
Rx buf len of hns3 driver only supports 2048 and 4096 at present, they are
discrete value and checked by driver.