netdev - Re: [PATCH] rtw88: Add delay on polling h2c command status bit

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <E3E792CF-AC1A-466E-A1B2-F1CFAE9BC673@canonical.com>
Date:   Tue, 7 Apr 2020 15:20:33 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Kalle Valo <kvalo@...eaurora.org>
Cc:     Tony Chuang <yhchuang@...ltek.com>,
        "David S. Miller" <davem@...emloft.net>,
        "open list:REALTEK WIRELESS DRIVER (rtw88)" 
        <linux-wireless@...r.kernel.org>,
        "open list:NETWORKING DRIVERS" <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] rtw88: Add delay on polling h2c command status bit



> On Apr 6, 2020, at 22:03, Kalle Valo <kvalo@...eaurora.org> wrote:
> 
> Kai-Heng Feng <kai.heng.feng@...onical.com> writes:
> 
>>> On Apr 6, 2020, at 21:24, Kalle Valo <kvalo@...eaurora.org> wrote:
>>> 
>>> Kai-Heng Feng <kai.heng.feng@...onical.com> writes:
>>> 
>>>>> On Apr 6, 2020, at 20:17, Kalle Valo <kvalo@...eaurora.org> wrote:
>>>>> 
>>>>> Kai-Heng Feng <kai.heng.feng@...onical.com> writes:
>>>>> 
>>>>>> --- a/drivers/net/wireless/realtek/rtw88/hci.h
>>>>>> +++ b/drivers/net/wireless/realtek/rtw88/hci.h
>>>>>> @@ -253,6 +253,10 @@ rtw_write8_mask(struct rtw_dev *rtwdev, u32
>>>>>> addr, u32 mask, u8 data)
>>>>>> 	rtw_write8(rtwdev, addr, set);
>>>>>> }
>>>>>> 
>>>>>> +#define rr8(addr)      rtw_read8(rtwdev, addr)
>>>>>> +#define rr16(addr)     rtw_read16(rtwdev, addr)
>>>>>> +#define rr32(addr)     rtw_read32(rtwdev, addr)
>>>>> 
>>>>> For me these macros reduce code readability, not improve anything. They
>>>>> hide the use of rtwdev variable, which is evil, and a name like rr8() is
>>>>> just way too vague. Please keep the original function names as is.
>>>> 
>>>> The inspiration is from another driver.
>>>> readx_poll_timeout macro only takes one argument for the op.
>>>> Some other drivers have their own poll_timeout implementation,
>>>> and I guess it makes sense to make one specific for rtw88.
>>> 
>>> I'm not even understanding the problem you are tying to fix with these
>>> macros. The upstream philosopyhy is to have the source code readable and
>>> maintainable, not to use minimal number of characters. There's a reason
>>> why we don't name our functions a(), b(), c() and so on.
>> 
>> The current h2c polling doesn't have delay between each interval, so
>> the polling is too fast and the following logic considers it's a
>> timeout.
>> The readx_poll_timeout() macro provides a generic mechanism to setup
>> an interval delay and timeout which is what we need here.
>> However readx_poll_timeout only accepts one parameter which usually is
>> memory address, while we need to pass both rtwdev and address.
>> 
>> So if hiding rtwdev is evil, we can roll our own variant of
>> readx_poll_timeout() to make the polling readable.
> 
> Can't you do:
> 
> ret = read_poll_timeout(rtw_read8, box_state,
>                        !((box_state >> box) & 0x1), 100,
>                        3000, false, rtw_dev, REG_HMETFR);
> 
> No ugly macros needed and it should function the same. But I did not
> test this in any way, so no idea if it even compiles.

Yes that will do. Didn't notice the recently added macro.

Will send v2.

Kai-Heng

> 
> -- 
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches