linux-kernel - Re: [PATCH v8 1/1] usb: cdns3: allocate TX FIFO size according to composite EP number

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Message-ID: <CAHrpEqQzBpNej+z6Td-snWtP1OqE8u_DAB6jAs-KAUBHmKcYkg@mail.gmail.com>
Date:   Wed, 27 Apr 2022 12:03:22 -0500
From:   Zhi Li <lznuaa@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Frank Li <Frank.Li@....com>, Peter Chen <peter.chen@...nel.org>,
        pawell@...ence.com, rogerq@...nel.org, a-govindraju@...com,
        linux-usb@...r.kernel.org, Jun Li <jun.li@....com>,
        kernel list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 1/1] usb: cdns3: allocate TX FIFO size according to
 composite EP number

On Wed, Apr 27, 2022 at 11:57 AM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Wed, Apr 27, 2022 at 11:35:25AM -0500, Frank Li wrote:
> > Some devices have USB compositions which may require multiple endpoints.
> > To get better performance, need bigger CDNS3_EP_BUF_SIZE.
> >
> > But bigger CDNS3_EP_BUF_SIZE may exceed total hardware FIFO size when
> > multiple endpoints.
> >
> > By introducing the check_config() callback, calculate CDNS3_EP_BUF_SIZE.
> >
> > Move CDNS3_EP_BUF_SIZE into cnds3_device: ep_buf_size
> > Combine CDNS3_EP_ISO_SS_BURST and CDNS3_EP_ISO_HS_MULT into
> > ecnds3_device:ep_iso_burst
> >
> > Using a simple algorithm to calculate ep_buf_size.
> > ep_buf_size = ep_iso_burst = (onchip_buffers - 2k) / (number of IN EP +
> > 1).
> >
> > Test at 8qxp:
> >
> >       Gadget                  ep_buf_size
> >
> >       RNDIS:                          5
> >       RNDIS+ACM:                      3
> >       Mass Storage + NCM + ACM        2
> >
> > Previous CDNS3_EP_BUF_SIZE is 4, RNDIS + ACM will be failure because
> > exceed FIFO memory.
> >
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> > Change from v1 to v2:
> >  Add safe check for mult, buffering and maxburst
>
> that's nice, but this is v8, not v2?

Sorry, It should be v2. I made a mistake with the title.

>
> confused,
>
> greg k-h