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    Subject[PATCH 4.14 082/165] media: em28xx: USB bulk packet size fix
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Brad Love <brad@nextdimension.cc>

    [ Upstream commit c7c7e8d7803406daa21e96d00c357de8b77b6764 ]

    Hauppauge em28xx bulk devices exhibit continuity errors and corrupted
    packets, when run in VMWare virtual machines. Unknown if other
    manufacturers bulk models exhibit the same issue. KVM/Qemu is unaffected.

    According to documentation the maximum packet multiplier for em28xx in bulk
    transfer mode is 256 * 188 bytes. This changes the size of bulk transfers
    to maximum supported value and have a bonus beneficial alignment.

    Before:

    After:

    This sets up USB to expect just as many bytes as the em28xx is set to emit.

    Successful usage under load afterwards natively and in both VMWare
    and KVM/Qemu virtual machines.

    Signed-off-by: Brad Love <brad@nextdimension.cc>
    Reviewed-by: Michael Ira Krufky <mkrufky@linuxtv.org>
    Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/media/usb/em28xx/em28xx.h | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/drivers/media/usb/em28xx/em28xx.h
    +++ b/drivers/media/usb/em28xx/em28xx.h
    @@ -191,7 +191,7 @@
    USB 2.0 spec says bulk packet size is always 512 bytes
    */
    #define EM28XX_BULK_PACKET_MULTIPLIER 384
    -#define EM28XX_DVB_BULK_PACKET_MULTIPLIER 384
    +#define EM28XX_DVB_BULK_PACKET_MULTIPLIER 94

    #define EM28XX_INTERLACED_DEFAULT 1


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