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

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Date:   Mon, 06 Apr 2020 17:03:00 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
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

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.

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