target/linux/brcm2708/patches-4.4/0495-Fixes-i2c_bcm2708-Write-to-FIFO-correctly-v2-1574.patch

   1 From 8ef9146c4479db1a672d7a88099e052a409624fa Mon Sep 17 00:00:00 2001
   2 From: Simon Maes <simonn.maes@gmail.com>
   3 Date: Mon, 29 Aug 2016 21:11:01 +0200
   4 Subject: [PATCH] Fixes i2c_bcm2708: Write to FIFO correctly - v2 (#1574)
   5
   6 * i2c: fix i2c_bcm2708: Clear FIFO before sending data
   7
   8 Make sure FIFO gets cleared before trying to send
   9 data in case of a repeated start (COMBINED=Y).
  10
  11 * i2c: fix i2c_bcm2708: Only write to FIFO when not full
  12
  13 Check if FIFO can accept data before writing.
  14 To avoid a peripheral read on the last iteration of a loop,
  15 both bcm2708_bsc_fifo_fill and ~drain are changed as well.
  16 ---
  17  drivers/i2c/busses/i2c-bcm2708.c | 8 ++++++--
  18  1 file changed, 6 insertions(+), 2 deletions(-)
  19
  20 --- a/drivers/i2c/busses/i2c-bcm2708.c
  21 +++ b/drivers/i2c/busses/i2c-bcm2708.c
  22 @@ -115,13 +115,13 @@ static inline void bcm2708_bsc_reset(str
  23
  24  static inline void bcm2708_bsc_fifo_drain(struct bcm2708_i2c *bi)
  25  {
  26 -       while ((bcm2708_rd(bi, BSC_S) & BSC_S_RXD) && (bi->pos < bi->msg->len))
  27 +       while ((bi->pos < bi->msg->len) && (bcm2708_rd(bi, BSC_S) & BSC_S_RXD))
  28                 bi->msg->buf[bi->pos++] = bcm2708_rd(bi, BSC_FIFO);
  29  }
  30
  31  static inline void bcm2708_bsc_fifo_fill(struct bcm2708_i2c *bi)
  32  {
  33 -       while ((bcm2708_rd(bi, BSC_S) & BSC_S_TXD) && (bi->pos < bi->msg->len))
  34 +       while ((bi->pos < bi->msg->len) && (bcm2708_rd(bi, BSC_S) & BSC_S_TXD))
  35                 bcm2708_wr(bi, BSC_FIFO, bi->msg->buf[bi->pos++]);
  36  }
  37
  38 @@ -155,6 +155,10 @@ static inline int bcm2708_bsc_setup(stru
  39                 if ( (bi->nmsgs > 1) &&
  40                         !(bi->msg[0].flags & I2C_M_RD) && (bi->msg[1].flags & I2C_M_RD) &&
  41                          (bi->msg[0].addr == bi->msg[1].addr) && (bi->msg[0].len <= 16)) {
  42 +
  43 +                       /* Clear FIFO */
  44 +                       bcm2708_wr(bi, BSC_C, BSC_C_CLEAR_1);
  45 +
  46                         /* Fill FIFO with entire write message (16 byte FIFO) */
  47                         while (bi->pos < bi->msg->len) {
  48                                 bcm2708_wr(bi, BSC_FIFO, bi->msg->buf[bi->pos++]);