target/linux/layerscape/patches-4.14/825-vfio-fsl-mc-Improve-send-mc-command-and-read-respons.patch

   1 From 703b2ca94467a029942fa478a38f0a14c8109766 Mon Sep 17 00:00:00 2001
   2 From: Bharat Bhushan <bharat.bhushan@nxp.com>
   3 Date: Fri, 1 Mar 2019 13:33:58 +0800
   4 Subject: [PATCH] vfio/fsl-mc: Improve send mc-command and read response
   5
   6 Actually there is no ordering need when reading response
   7 from mc-portal. Similarly when writing the mc-command,
   8 ordering needed before command is submitted.
   9
  10 This patch removes un-necessary barriers, response is read
  11 relaxed and maintain ordering when submit command. This also
  12 fixes compilation issue with newer kernel.
  13
  14 Signed-off-by: Bharat Bhushan <Bharat.Bhushan@nxp.com>
  15 Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
  16 ---
  17  drivers/vfio/fsl-mc/vfio_fsl_mc.c | 13 +++++++------
  18  1 file changed, 7 insertions(+), 6 deletions(-)
  19
  20 --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
  21 +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
  22 @@ -331,9 +331,7 @@ static int vfio_fsl_mc_dprc_wait_for_res
  23                 u64 header;
  24                 struct mc_cmd_header *resp_hdr;
  25
  26 -               __iormb();
  27 -               header = readq(ioaddr);
  28 -               __iormb();
  29 +               header = cpu_to_le64(readq_relaxed(ioaddr));
  30
  31                 resp_hdr = (struct mc_cmd_header *)&header;
  32                 status = (enum mc_cmd_status)resp_hdr->status;
  33 @@ -353,9 +351,12 @@ static int vfio_fsl_mc_send_command(void
  34  {
  35         int i;
  36
  37 -       /* Write at command header in the end */
  38 -       for (i = 7; i >= 0; i--)
  39 -               writeq(cmd_data[i], ioaddr + i * sizeof(uint64_t));
  40 +       /* Write at command parameter into portal */
  41 +       for (i = 7; i >= 1; i--)
  42 +               writeq_relaxed(cmd_data[i], ioaddr + i * sizeof(uint64_t));
  43 +
  44 +       /* Write command header in the end */
  45 +       writeq(cmd_data[0], ioaddr);
  46
  47         /* Wait for response before returning to user-space
  48          * This can be optimized in future to even prepare response