Commits on Nov 13, 2024

1. can: mcp251xfd: mcp251xfd_ring_alloc(): fix coalescing configuration … …

   …when switching CAN modes
   
   commit eb9a839 upstream.
   
   Since commit 50ea544 ("can: mcp251xfd: fix ring configuration
   when switching from CAN-CC to CAN-FD mode"), the current ring and
   coalescing configuration is passed to can_ram_get_layout(). That fixed
   the issue when switching between CAN-CC and CAN-FD mode with
   configured ring (rx, tx) and/or coalescing parameters (rx-frames-irq,
   tx-frames-irq).
   
   However 50ea544 ("can: mcp251xfd: fix ring configuration when
   switching from CAN-CC to CAN-FD mode"), introduced a regression when
   switching CAN modes with disabled coalescing configuration: Even if
   the previous CAN mode has no coalescing configured, the new mode is
   configured with active coalescing. This leads to delayed receiving of
   CAN-FD frames.
   
   This comes from the fact, that ethtool uses usecs = 0 and max_frames =
   1 to disable coalescing, however the driver uses internally
   priv->{rx,tx}_obj_num_coalesce_irq = 0 to indicate disabled
   coalescing.
   
   Fix the regression by assigning struct ethtool_coalesce
   ec->{rx,tx}_max_coalesced_frames_irq = 1 if coalescing is disabled in
   the driver as can_ram_get_layout() expects this.
   
   Reported-by: https://github.com/vdh-robothania
   Closes: raspberrypi#6407
   Fixes: 50ea544 ("can: mcp251xfd: fix ring configuration when switching from CAN-CC to CAN-FD mode")
   Cc: [email protected]
   Reviewed-by: Simon Horman <[email protected]>
   Link: https://patch.msgid.link/20241025-mcp251xfd-fix-coalesing-v1-1-9d11416de1df@pengutronix.de
   Signed-off-by: Marc Kleine-Budde <[email protected]>

   

   marckleinebudde authored and pelwell committed Nov 13, 2024
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