git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From eb9a839b3d8a989be5970035a5cf29bcd6ffd24d Mon Sep 17 00:00:00 2001
   2 From: Marc Kleine-Budde <mkl@pengutronix.de>
   3 Date: Fri, 25 Oct 2024 14:34:40 +0200
   4 Subject: can: mcp251xfd: mcp251xfd_ring_alloc(): fix coalescing configuration when switching CAN modes
   5
   6 From: Marc Kleine-Budde <mkl@pengutronix.de>
   7
   8 commit eb9a839b3d8a989be5970035a5cf29bcd6ffd24d upstream.
   9
  10 Since commit 50ea5449c563 ("can: mcp251xfd: fix ring configuration
  11 when switching from CAN-CC to CAN-FD mode"), the current ring and
  12 coalescing configuration is passed to can_ram_get_layout(). That fixed
  13 the issue when switching between CAN-CC and CAN-FD mode with
  14 configured ring (rx, tx) and/or coalescing parameters (rx-frames-irq,
  15 tx-frames-irq).
  16
  17 However 50ea5449c563 ("can: mcp251xfd: fix ring configuration when
  18 switching from CAN-CC to CAN-FD mode"), introduced a regression when
  19 switching CAN modes with disabled coalescing configuration: Even if
  20 the previous CAN mode has no coalescing configured, the new mode is
  21 configured with active coalescing. This leads to delayed receiving of
  22 CAN-FD frames.
  23
  24 This comes from the fact, that ethtool uses usecs = 0 and max_frames =
  25 1 to disable coalescing, however the driver uses internally
  26 priv->{rx,tx}_obj_num_coalesce_irq = 0 to indicate disabled
  27 coalescing.
  28
  29 Fix the regression by assigning struct ethtool_coalesce
  30 ec->{rx,tx}_max_coalesced_frames_irq = 1 if coalescing is disabled in
  31 the driver as can_ram_get_layout() expects this.
  32
  33 Reported-by: https://github.com/vdh-robothania
  34 Closes: https://github.com/raspberrypi/linux/issues/6407
  35 Fixes: 50ea5449c563 ("can: mcp251xfd: fix ring configuration when switching from CAN-CC to CAN-FD mode")
  36 Cc: stable@vger.kernel.org
  37 Reviewed-by: Simon Horman <horms@kernel.org>
  38 Link: https://patch.msgid.link/20241025-mcp251xfd-fix-coalesing-v1-1-9d11416de1df@pengutronix.de
  39 Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
  40 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  41 ---
  42  drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c |    8 +++++---
  43  1 file changed, 5 insertions(+), 3 deletions(-)
  44
  45 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c
  46 +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c
  47 @@ -2,7 +2,7 @@
  48  //
  49  // mcp251xfd - Microchip MCP251xFD Family CAN controller driver
  50  //
  51 -// Copyright (c) 2019, 2020, 2021 Pengutronix,
  52 +// Copyright (c) 2019, 2020, 2021, 2024 Pengutronix,
  53  //               Marc Kleine-Budde <kernel@pengutronix.de>
  54  //
  55  // Based on:
  56 @@ -483,9 +483,11 @@ int mcp251xfd_ring_alloc(struct mcp251xf
  57                 };
  58                 const struct ethtool_coalesce ec = {
  59                         .rx_coalesce_usecs_irq = priv->rx_coalesce_usecs_irq,
  60 -                       .rx_max_coalesced_frames_irq = priv->rx_obj_num_coalesce_irq,
  61 +                       .rx_max_coalesced_frames_irq = priv->rx_obj_num_coalesce_irq == 0 ?
  62 +                               1 : priv->rx_obj_num_coalesce_irq,
  63                         .tx_coalesce_usecs_irq = priv->tx_coalesce_usecs_irq,
  64 -                       .tx_max_coalesced_frames_irq = priv->tx_obj_num_coalesce_irq,
  65 +                       .tx_max_coalesced_frames_irq = priv->tx_obj_num_coalesce_irq == 0 ?
  66 +                               1 : priv->tx_obj_num_coalesce_irq,
  67                 };
  68                 struct can_ram_layout layout;
  69