target/linux/generic/backport-6.1/781-v6.6-01-net-dsa-qca8k-fix-regmap-bulk-read-write-methods-on-.patch

   1 From 5652d1741574eb89cc02576e50ee3e348bd6dd77 Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Marek=20Beh=C3=BAn?= <kabel@kernel.org>
   3 Date: Wed, 4 Oct 2023 11:19:03 +0200
   4 Subject: [PATCH 1/2] net: dsa: qca8k: fix regmap bulk read/write methods on
   5  big endian systems
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 Commit c766e077d927 ("net: dsa: qca8k: convert to regmap read/write
  11 API") introduced bulk read/write methods to qca8k's regmap.
  12
  13 The regmap bulk read/write methods get the register address in a buffer
  14 passed as a void pointer parameter (the same buffer contains also the
  15 read/written values). The register address occupies only as many bytes
  16 as it requires at the beginning of this buffer. For example if the
  17 .reg_bits member in regmap_config is 16 (as is the case for this
  18 driver), the register address occupies only the first 2 bytes in this
  19 buffer, so it can be cast to u16.
  20
  21 But the original commit implementing these bulk read/write methods cast
  22 the buffer to u32:
  23   u32 reg = *(u32 *)reg_buf & U16_MAX;
  24 taking the first 4 bytes. This works on little endian systems where the
  25 first 2 bytes of the buffer correspond to the low 16-bits, but it
  26 obviously cannot work on big endian systems.
  27
  28 Fix this by casting the beginning of the buffer to u16 as
  29    u32 reg = *(u16 *)reg_buf;
  30
  31 Fixes: c766e077d927 ("net: dsa: qca8k: convert to regmap read/write API")
  32 Signed-off-by: Marek Behún <kabel@kernel.org>
  33 Tested-by: Christian Marangi <ansuelsmth@gmail.com>
  34 Reviewed-by: Christian Marangi <ansuelsmth@gmail.com>
  35 Signed-off-by: David S. Miller <davem@davemloft.net>
  36 ---
  37  drivers/net/dsa/qca/qca8k-8xxx.c | 4 ++--
  38  1 file changed, 2 insertions(+), 2 deletions(-)
  39
  40 --- a/drivers/net/dsa/qca/qca8k-8xxx.c
  41 +++ b/drivers/net/dsa/qca/qca8k-8xxx.c
  42 @@ -504,8 +504,8 @@ qca8k_bulk_read(void *ctx, const void *r
  43                 void *val_buf, size_t val_len)
  44  {
  45         int i, count = val_len / sizeof(u32), ret;
  46 -       u32 reg = *(u32 *)reg_buf & U16_MAX;
  47         struct qca8k_priv *priv = ctx;
  48 +       u32 reg = *(u16 *)reg_buf;
  49
  50         if (priv->mgmt_master &&
  51             !qca8k_read_eth(priv, reg, val_buf, val_len))
  52 @@ -526,8 +526,8 @@ qca8k_bulk_gather_write(void *ctx, const
  53                         const void *val_buf, size_t val_len)
  54  {
  55         int i, count = val_len / sizeof(u32), ret;
  56 -       u32 reg = *(u32 *)reg_buf & U16_MAX;
  57         struct qca8k_priv *priv = ctx;
  58 +       u32 reg = *(u16 *)reg_buf;
  59         u32 *val = (u32 *)val_buf;
  60
  61         if (priv->mgmt_master &&