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From: Oliver Neukum <oneukum@suse.com>
To: Muni Sekhar <munisekharrms@gmail.com>,
	kernelnewbies <kernelnewbies@kernelnewbies.org>,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: read() via USB bus
Date: Mon, 9 Aug 2021 10:15:29 +0200	[thread overview]
Message-ID: <8923f2b8-0be0-ffbf-70a4-c03c9a02d58a@suse.com> (raw)
In-Reply-To: <CAHhAz+jKREfXERKj7XB7U3Wh1g4STO2Dt0qnMkcPV5nXB3_bwg@mail.gmail.com>


On 09.08.21 09:58, Muni Sekhar wrote:
> Hi all,
>
> PCIe memory mapped registers can be read via readb(), readw(), readl()
> kernel API's. Similarly what are the kernel API to read the device
> registers via USB bus
>

Hi,

I am afraid this is based on a fundamental misunderstanding on how
USB works. It is based on passing messages, not reading and writing
registers.

USB devices are primarily based on endpoints, not registers. A literal
answer to your question would point you to the clear/set/get_feature
standard requests of chapter 9 of the specification, but that really
will not help you, as you are making assumption that fundamentally
do not apply.

I hope this list stays friendly to newcomers and we will answer
specific questions, but at this point I must advise you to first
read an introductory book.

    HTH
        Oliver



  reply	other threads:[~2021-08-09  8:15 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-09  7:58 Muni Sekhar
2021-08-09  8:15 ` Oliver Neukum [this message]
2021-08-09  8:44   ` Greg KH
2021-08-12  9:45     ` LDD 3rd ed. - It was: " Fabio M. De Francesco
2021-08-12 10:13       ` Valdis Klētnieks
2021-08-12 10:18       ` Greg KH
2021-08-12 10:26         ` Robert P. J. Day
2021-08-09 16:19   ` Muni Sekhar
2021-08-10 14:13   ` Muni Sekhar
2021-08-10 14:20     ` Oliver Neukum
     [not found]       ` <CAHhAz+ioThu3v4VW6LVqFn9MhgNaqv=qDoxh8Orkw2LOEC_JYA@mail.gmail.com>
2021-08-11 10:04         ` Oliver Neukum

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