linux-kernel - RE: [EXT] RE: [PATCH 1/1] usb: cdns3: fix super speed mass storage gadget device failure at imx8qm

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Message-ID: <AM6PR04MB48381649089FA348D8AB967588869@AM6PR04MB4838.eurprd04.prod.outlook.com>
Date:   Wed, 22 Mar 2023 14:21:31 +0000
From:   Frank Li <frank.li@....com>
To:     Pawel Laszczak <pawell@...ence.com>,
        Peter Chen <peter.chen@...nel.org>,
        Roger Quadros <rogerq@...nel.org>,
        Aswath Govindraju <a-govindraju@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:CADENCE USB3 DRD IP DRIVER" <linux-usb@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
CC:     "imx@...ts.linux.dev" <imx@...ts.linux.dev>
Subject: RE: [EXT] RE: [PATCH 1/1] usb: cdns3: fix super speed mass storage
 gadget device failure at imx8qm



> -----Original Message-----
> From: Pawel Laszczak <pawell@...ence.com>
> Sent: Wednesday, March 22, 2023 5:56 AM
> To: Frank Li <frank.li@....com>; Peter Chen <peter.chen@...nel.org>;
> Roger Quadros <rogerq@...nel.org>; Aswath Govindraju <a-
> govindraju@...com>; Greg Kroah-Hartman <gregkh@...uxfoundation.org>;
> open list:CADENCE USB3 DRD IP DRIVER <linux-usb@...r.kernel.org>; open
> list <linux-kernel@...r.kernel.org>
> Cc: imx@...ts.linux.dev
> Subject: [EXT] RE: [PATCH 1/1] usb: cdns3: fix super speed mass storage
> gadget device failure at imx8qm
> 
> Caution: EXT Email
> 
> >>The mass storage gadget has one IN and one OUT endpoint. The below
> >>(Fixes) commit aimed to utilize all hardware FIFO to support composited
> >>gadget devices. This resulted in an ep_buf_size of 15 when a single
> >>gadget was enabled, such as the mass storage gadget.
> >>
> >>However, it was found that there are unknown limitations on the imx8qm
> >>and imx8qxp B0 platforms. The device would fail to work if ep_buf_size
> >>exceeded 9.
> >>
> >>To resolve this issue, this patch reverts to the old settings used
> >>before the below commit for the imx8qm and imx8qxp B0 platforms.
> >>
> >>Fixes: dce49449e04f ("usb: cdns3: allocate TX FIFO size according to
> >>composite EP number")
> >>
> >>Signed-off-by: Frank Li <Frank.Li@....com>
> >>---
> >>
> >>I hope cdns engineer, such as pawell@...ence.com help identfy the root
> >>cause.
> >>Look like old version ip use more memory then what ep_cfg show.
> >>
> >> drivers/usb/cdns3/cdns3-gadget.c | 11 +++++++++++
> >> 1 file changed, 11 insertions(+)
> >>
> >>diff --git a/drivers/usb/cdns3/cdns3-gadget.c
> >>b/drivers/usb/cdns3/cdns3- gadget.c index 5adcb349718c..497c8e87dabf
> >>100644
> >>--- a/drivers/usb/cdns3/cdns3-gadget.c
> >>+++ b/drivers/usb/cdns3/cdns3-gadget.c
> >>@@ -3005,6 +3005,17 @@ static int cdns3_gadget_check_config(struct
> >>usb_gadget *gadget)
> >>      priv_dev->ep_buf_size = priv_dev->ep_iso_burst =
> >>                      (priv_dev->onchip_buffers - 2) / (n_in + 1);
> >>
> >>+     /*
> >>+      * There are unknown hardware limition: when work at super speed
> >>mode,
> >>+      * ep_buffer_size can't bigger than 9 for one IN and OUT case at
> >>i.MX8QM
> >>+      * and i.MX8QXP B0, which report there are 32k memory.
> >>+      * Rollback to original settings for the these chipes.
> >>+      */
> >>+     if (priv_dev->dev_ver < DEV_VER_V2) {
> >>+             priv_dev->ep_buf_size = min_t(u8, priv_dev->ep_buf_size, 4);
> >>+             priv_dev->ep_iso_burst = min_t(u8, priv_dev->ep_iso_burst,
> >>3);
> >>+     }
> >>+
> >>      return 0;
> >> }
> >
> >I'm not sure whether you have 32KB. I remember that you had a Soc which
> >have only 18KB on-chip memory and value in usb_cap2 was incorrect.
> >It was the reason why the on-chip-buff-size property has been added to
> >driver.
> >
> >Please confirm that you have 32KB, then I will recreate such test on my
> testing
> >board.
> >
> 
> I've made the MSC test with the following endpoint configuration;
> [ 6732.999537] cdns-usb3 cdns-usb3.1: Configure ep1in: with val 74000e05
> [ 6732.999565] cdns-usb3 cdns-usb3.1: Configure ep1out: with val 74000e15
> 
> So, I used the 14 buffers per endpoint and run bonnie++ as tester.
> I didn't find any issue.

Problem only happen at QM and QXP B0 and need work at *super speed* mode.
Enumerate will be fail and continues reset.  

Highspeed mode work. 

I suspect 32KB problem because QXP C0 report is 18K.  It doesn't make sense to
reduce to 18K from 32k at QXP C0.

But it work when IN/OUT is 9K.  9+9+2k(EP0) should bigger than 18K.  Let me try
Check IC design what's exact number in QM and QXPB0.

> 
> Regards,
> Pawel
> >>
> >>--
> >>2.34.1