From c7c7e8d7803406daa21e96d00c357de8b77b6764 Mon Sep 17 00:00:00 2001
From: Brad Love <brad@nextdimension.cc>
Date: Thu, 4 Jan 2018 19:04:13 -0500
Subject: [PATCH] media: em28xx: USB bulk packet size fix
Git-commit: c7c7e8d7803406daa21e96d00c357de8b77b6764
Patch-mainline: v4.17-rc1
References: bsc#1051510

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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
@@ -190,7 +190,7 @@
    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