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From: Norihiko Hama <norihiko.hama@alpsalpine.com>
To: Greg KH <gregkh@linuxfoundation.org>
CC: "stern@rowland.harvard.edu" <stern@rowland.harvard.edu>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"usb-storage@lists.one-eyed-alien.net"
	<usb-storage@lists.one-eyed-alien.net>, "linux-kernel@vger.kernel.org"
	<linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] usb-storage: Optimize scan delay more precisely
Thread-Topic: [PATCH] usb-storage: Optimize scan delay more precisely
Thread-Index: AQHagAnskZ+PrXZ1a0CyN6BGkMIiXrFLFjOAgAAcfLCAAAKHgIAAAT8g
Date: Wed, 27 Mar 2024 07:57:52 +0000
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References: <20240327055130.43206-1-Norihiko.Hama@alpsalpine.com>
 <2024032757-surcharge-grime-d3dd@gregkh>
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On Wed, Mar 27, 2024 at 07:39:55AM +-0000, Norihiko Hama wrote:
+AD4- +AD4- +AD4- Sorry, but module parameters are from the 1990's, we will=
 not go back to that if at all possible as it's not easy to maintain and wi=
ll not work properly for multiple devices.
+AD4- +AD4- +AD4-
+AD4- +AD4- +AD4- I can understand wanting something between 1 and 0 second=
s, but adding yet-another-option isn't probably the best way, sorry.
+AD4- +AD4- 1 second does not meet with performance requirement.
+AD4-
+AD4- Who is requiring such a performance requirement?  The USB specificati=
on?
+AD4- Or something else?
This is our customer requirement.

+AD4- +AD4- I have no good idea except module parameter so that we can main=
tain backward compatibility but be configurable out of module.
+AD4- +AD4- Do you have any other better solution?
+AD4- How long do you exactly need to wait?  Why not figure out how long th=
e device takes and if it fails, slowly back off until the full time delay h=
appens and then you can abort?
It's IOP issue and difficult to figure out because it depends on device its=
elf.
I know we have multiple devices with delay+AF8-use+AD0-0, but then it's rec=
overed and detected by reset after 30s timeout, that is too long than 1 sec=
.