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From: "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>
To: Pkshih <pkshih@realtek.com>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	"johannes@sipsolutions.net" <johannes@sipsolutions.net>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	"neojou@gmail.com" <neojou@gmail.com>,
	"kvalo@kernel.org" <kvalo@kernel.org>,
	"tony0620emma@gmail.com" <tony0620emma@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"martin.blumenstingl@googlemail.com" 
	<martin.blumenstingl@googlemail.com>,
	"linux@ulli-kroll.de" <linux@ulli-kroll.de>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH 02/10] rtw88: Drop rf_lock
Date: Fri, 20 May 2022 08:54:35 +0200	[thread overview]
Message-ID: <20220520065435.GB25578@pengutronix.de> (raw)
In-Reply-To: <af80039404cb3eb9dd036ab5734ddea95d31cf49.camel@realtek.com>

On Fri, May 20, 2022 at 03:49:06AM +0000, Pkshih wrote:
> On Wed, 2022-05-18 at 10:23 +0200, Sascha Hauer wrote:
> > The rtwdev->rf_lock spinlock protects the rf register accesses in
> > rtw_read_rf() and rtw_write_rf(). Most callers of these functions hold
> > rtwdev->mutex already with the exception of the callsites in the debugfs
> > code. The debugfs code doesn't justify an extra lock, so acquire the mutex
> > there as well before calling rf register accessors and drop the now
> > unnecessary spinlock.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > ---
> >  drivers/net/wireless/realtek/rtw88/debug.c | 11 +++++++++++
> >  drivers/net/wireless/realtek/rtw88/hci.h   |  9 +++------
> >  drivers/net/wireless/realtek/rtw88/main.c  |  1 -
> >  drivers/net/wireless/realtek/rtw88/main.h  |  3 ---
> >  4 files changed, 14 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/net/wireless/realtek/rtw88/debug.c
> > b/drivers/net/wireless/realtek/rtw88/debug.c
> > index 1a52ff585fbc7..ba5ba852efb8c 100644
> > --- a/drivers/net/wireless/realtek/rtw88/debug.c
> > +++ b/drivers/net/wireless/realtek/rtw88/debug.c
> > 
> 
> [...]
> 
> > @@ -523,6 +527,8 @@ static int rtw_debug_get_rf_dump(struct seq_file *m, void *v)
> >  	u32 addr, offset, data;
> >  	u8 path;
> >  
> > +	mutex_lock(&rtwdev->mutex);
> > +
> >  	for (path = 0; path < rtwdev->hal.rf_path_num; path++) {
> >  		seq_printf(m, "RF path:%d\n", path);
> >  		for (addr = 0; addr < 0x100; addr += 4) {
> > @@ -537,6 +543,8 @@ static int rtw_debug_get_rf_dump(struct seq_file *m, void *v)
> >  		seq_puts(m, "\n");
> >  	}
> >  
> > +	mutex_unlock(&rtwdev->mutex);
> > +
> >  	return 0;
> >  }
> > 
> 
> This will take time to dump all RF registers for debugging
> purpose. For PCI interface, I think this would be okay.
> Could you try to dump registers via debufs while you are
> using a USB WiFi device, such as play Youtube or download files...

I just did a ping and iperf test while doing a:

while true; do cat /sys/kernel/debug/ieee80211/phy0/rtw88/rf_dump ; done

The register dumping has no influence on neither the throughput or the
latency.

Adding some debugging to the mutex_lock also tells why: rtwdev->mutex
isn't acquired for normal rx/tx. It is only acquired every two seconds
or so.

So I would say adding the mutex_lock around the register dump is not a
problem. If latency is a concern we could still move the mutex_lock()
into the loop.

Sascha

-- 
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  reply	other threads:[~2022-05-20  6:54 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-18  8:23 [PATCH 00/10] RTW88: Add support for USB variants Sascha Hauer
2022-05-18  8:23 ` [PATCH 01/10] rtw88: Call rtw_fw_beacon_filter_config() with rtwdev->mutex held Sascha Hauer
2022-05-18  8:23 ` [PATCH 02/10] rtw88: Drop rf_lock Sascha Hauer
2022-05-20  3:49   ` Pkshih
2022-05-20  6:54     ` s.hauer [this message]
2022-05-18  8:23 ` [PATCH 03/10] rtw88: Drop h2c.lock Sascha Hauer
2022-05-18  8:23 ` [PATCH 04/10] rtw88: Drop coex mutex Sascha Hauer
2022-05-18  8:23 ` [PATCH 05/10] rtw88: Do not access registers while atomic Sascha Hauer
2022-05-20  6:06   ` Pkshih
2022-05-20  7:07     ` s.hauer
2022-05-20 17:32   ` Larry Finger
2022-05-18  8:23 ` [PATCH 06/10] rtw88: Add common USB chip support Sascha Hauer
2022-05-18  8:32   ` Sascha Hauer
2022-05-18  8:34     ` Johannes Berg
2022-05-19 13:58       ` Sascha Hauer
2022-05-20  7:39   ` Pkshih
2022-05-20  8:51     ` s.hauer
2022-05-20  9:23       ` Pkshih
2022-05-20 18:33   ` Larry Finger
2022-05-23  4:07   ` Hans Ulli Kroll
2022-05-18  8:23 ` [PATCH 07/10] rtw88: Add rtw8723du chipset support Sascha Hauer
2022-05-18 16:55   ` kernel test robot
2022-05-20  7:47   ` Pkshih
2022-05-20  8:16     ` s.hauer
2022-05-30  6:34   ` Icenowy Zheng
2022-05-18  8:23 ` [PATCH 08/10] rtw88: Add rtw8821cu " Sascha Hauer
2022-05-20  7:56   ` Pkshih
2022-05-18  8:23 ` [PATCH 09/10] rtw88: Add rtw8822bu " Sascha Hauer
2022-05-20  7:58   ` Pkshih
2022-05-23 11:56   ` Rin Cat (鈴猫)
2022-05-23 12:34     ` Sascha Hauer
2022-05-18  8:23 ` [PATCH 10/10] rtw88: Add rtw8822cu " Sascha Hauer
2022-05-20  8:03   ` Pkshih
2022-05-20  8:56     ` s.hauer
2022-05-23  4:07 ` [PATCH 00/10] RTW88: Add support for USB variants Hans Ulli Kroll
2022-05-23  6:53   ` Sascha Hauer
2022-05-23 11:39     ` Ping-Ke Shih
2022-05-24  6:54       ` s.hauer
2022-05-23 10:13   ` Sascha Hauer
2022-05-30  9:25 ` Kalle Valo
2022-05-30  9:52   ` Sascha Hauer
2022-05-30 10:07     ` Kalle Valo
2022-05-30 10:16       ` Sascha Hauer

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