linux-kernel - Re: [PATCH v4 01/13] phy: usb: EHCI DMA may lose a burst of DMA data for 7255xA0 family

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <7f52c9eb-7cd6-db19-f67e-1d8e95621c4c@gmail.com>
Date:   Fri, 3 Jan 2020 10:22:54 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Al Cooper <alcooperx@...il.com>, linux-kernel@...r.kernel.org
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@...adcom.com>,
        Srinath Mannam <srinath.mannam@...adcom.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 01/13] phy: usb: EHCI DMA may lose a burst of DMA data
 for 7255xA0 family

On 1/3/20 10:17 AM, Al Cooper wrote:
> When the EHCI controller received a 512 byte USB packet that
> had to be broken into 2 256 byte bursts across the SCB bus AND
> there was a following 512 byte USB packet, the second burst of
> data from the first packet was sometimes being lost. If the
> burst size was changed to 128 bytes via the EBR_SCB_SIZE field
> in the USB_CTRL_EBRIDGE register we'd see the 4th 128 byte burst
> of the first packet being lost. This problem became much worse
> if other threads were running that accessed memory, like a memcpy
> test. Setting the EBR_SCB_SIZE to 512, which prevents breaking
> the EHCI USB packet (max size of 512 bytes) into bursts, fixed
> the problem.
> 
> Signed-off-by: Al Cooper <alcooperx@...il.com>

Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
-- 
Florian