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

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Message-Id: <98FD848B-7F8A-4D2A-8265-CBF877011A5C@canonical.com>
Date:   Mon, 6 Apr 2020 19:56:30 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Tony Chuang <yhchuang@...ltek.com>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        "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

Hi Tony,

> On Apr 6, 2020, at 19:01, Tony Chuang <yhchuang@...ltek.com> wrote:
> 
>> Subject: [PATCH] rtw88: Add delay on polling h2c command status bit
>> 
>> On some systems we can constanly see rtw88 complains:
>> [39584.721375] rtw_pci 0000:03:00.0: failed to send h2c command
>> 
>> Increase interval of each check to wait the status bit really changes.
>> 
>> While at it, add some helpers so we can use standarized
>> readx_poll_timeout() macro.
>> 
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>> ---
>> drivers/net/wireless/realtek/rtw88/fw.c  | 12 ++++++------
>> drivers/net/wireless/realtek/rtw88/hci.h |  4 ++++
>> 2 files changed, 10 insertions(+), 6 deletions(-)
>> 
>> diff --git a/drivers/net/wireless/realtek/rtw88/fw.c
>> b/drivers/net/wireless/realtek/rtw88/fw.c
>> index 05c430b3489c..bc9982e77524 100644
>> --- a/drivers/net/wireless/realtek/rtw88/fw.c
>> +++ b/drivers/net/wireless/realtek/rtw88/fw.c
>> @@ -2,6 +2,8 @@
>> /* Copyright(c) 2018-2019  Realtek Corporation
>>  */
>> 
>> +#include <linux/iopoll.h>
>> +
>> #include "main.h"
>> #include "coex.h"
>> #include "fw.h"
>> @@ -193,8 +195,8 @@ static void rtw_fw_send_h2c_command(struct
>> rtw_dev *rtwdev,
>> 	u8 box;
>> 	u8 box_state;
>> 	u32 box_reg, box_ex_reg;
>> -	u32 h2c_wait;
>> 	int idx;
>> +	int ret;
>> 
>> 	rtw_dbg(rtwdev, RTW_DBG_FW,
>> 		"send H2C content %02x%02x%02x%02x %02x%02x%02x%02x\n",
>> @@ -226,12 +228,10 @@ static void rtw_fw_send_h2c_command(struct
>> rtw_dev *rtwdev,
>> 		goto out;
>> 	}
>> 
>> -	h2c_wait = 20;
>> -	do {
>> -		box_state = rtw_read8(rtwdev, REG_HMETFR);
>> -	} while ((box_state >> box) & 0x1 && --h2c_wait > 0);
>> +	ret = readx_poll_timeout(rr8, REG_HMETFR, box_state,
>> +				 !((box_state >> box) & 0x1), 100, 3000);
>> 
>> -	if (!h2c_wait) {
>> +	if (ret) {
>> 		rtw_err(rtwdev, "failed to send h2c command\n");
>> 		goto out;
>> 	}
>> diff --git a/drivers/net/wireless/realtek/rtw88/hci.h
>> b/drivers/net/wireless/realtek/rtw88/hci.h
>> index 2cba327e6218..24062c7079c6 100644
>> --- 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)
>> +
>> static inline enum rtw_hci_type rtw_hci_type(struct rtw_dev *rtwdev)
>> {
>> 	return rtwdev->hci.type;
>> --
> 
> I think the timeout is because the H2C is triggered when the lower 4 bytes are written.
> So, we probably should write h2c[4] ~ h2c[7] before h2c[0] ~ h2c[3].

I can still see "failed to send h2c command" with the following patch:

diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
index eb7e623c811a..a296c860045f 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.c
+++ b/drivers/net/wireless/realtek/rtw88/fw.c
@@ -240,10 +240,10 @@ static void rtw_fw_send_h2c_command(struct rtw_dev *rtwdev,
                goto out;
        }

-       for (idx = 0; idx < 4; idx++)
-               rtw_write8(rtwdev, box_reg + idx, h2c[idx]);
        for (idx = 0; idx < 4; idx++)
                rtw_write8(rtwdev, box_ex_reg + idx, h2c[idx + 4]);
+       for (idx = 0; idx < 4; idx++)
+               rtw_write8(rtwdev, box_reg + idx, h2c[idx]);

        if (++rtwdev->h2c.last_box_num >= 4)
                rtwdev->h2c.last_box_num = 0;


> 
> But this delay still works, I think you can keep it, and reorder the h2c write sequence.
> 
> Yen-Hsuan