can: mcp251xfd: mcp251xfd_ring_alloc(): fix coalescing configuration … #6466
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…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]>
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…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: #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