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Sender: Larry Finger <larry.finger@gmail.com>
Message-ID: <ddaf8f07-5a7b-49a4-8ec1-2a28eee2279e@lwfinger.net>
Date: Fri, 29 Dec 2023 15:36:07 -0600
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Subject: Re: [PATCH] wifi: rtlwifi: rtl_usb: Use sync register writes
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To: Bitterblue Smith <rtl8821cerfe2@gmail.com>,
 "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Cc: Ping-Ke Shih <pkshih@realtek.com>
References: <f806007e-8fba-4f29-8a38-f81d04bd4fb8@gmail.com>
From: Larry Finger <Larry.Finger@lwfinger.net>
In-Reply-To: <f806007e-8fba-4f29-8a38-f81d04bd4fb8@gmail.com>
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On 12/29/23 14:51, Bitterblue Smith wrote:
> Currently rtl_usb performs register writes using the async
> usb_submit_urb() function. This appears to work fine for the RTL8192CU,
> but the RTL8192DU (soon to be supported by rtlwifi) has a problem:
> it transmits everything at the 1M rate in the 2.4 GHz band. (The 5 GHZ
> band is still untested.)
> 
> With this patch, rtl_usb performs the register writes using the
> synchronous usb_control_msg() function, and the RTL8192DU works
> normally. The RTL8192CU still works.
> 
> The vendor drivers use the async writes in only one function,
> rtl8192du_trigger_gpio_0 / rtl8192cu_trigger_gpio_0, which probably
> doesn't even run in real life. They use sync writes everywhere else.
> 
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
> ---
> 
> Larry, do you remember why, back in 2011, you chose to implement the
> async writes?

Bitterblue,

That was code provided by Realtek from their USB group. I think they were in 
China, not Taiwan. At least the PCI and USB groups were in different countries. 
They provided the code, and I just cleaned it up. tested it, and submitted it. 
If the sync function works for the cu and du chips, go for it.

Larry