[PATCH v2 00/10] can: rcar_canfd: Add support for Transceiver Delay Compensation

[Geert Uytterhoeven <geert+renesas@glider.be>]

	Hi all,

This patch series adds CAN-FD Transceiver Delay Compensation support to
the R-Car CAN-FD driver, after the customary cleanups and refactorings.

Changes compared to v1:
  - Dropped patch "can: rcar_canfd: Use ndev parameter in
    rcar_canfd_set_bittiming()",
  - New patch "[PATCH v2 02/10] can: rcar_canfd: Remove bittiming debug
    prints",
  - New patch "[PATCH v2 07/10] can: rcar_canfd: Rename
    rcar_canfd_setrnc() to rcar_canfd_set_rnc()",
  - Add Reviewed-by,
  - Replace function-like RCANFD_F_*() macros by rcar_canfd_f_*()
    inline functions,
  - Replace function-like macro RCANFD_FDSTS_TDCR() by bitmask
    RCANFD_FDSTS_TDCR and helper function rcar_canfd_get_tdcr(),
  - Replace function-like macro RCANFD_FDSTS_TDCVF() by two bit
    definitions,
  - Drop debug print of tdc mode and tdco value.

This has been tested on R-Car V4H (White Hawk), V4M (Gray Hawk Single),
and E3 (Ebisu-4D[2]), using various data bit rates.  Without proper TDC
configuration, transmitting at 8 Mbps makes the CAN-FD controller enter
BUS-OFF state.  The TDCV value as measured by the CAN-FD controller is 4
on all boards tested (base clock 40 MHz, i.e. 25 ns period), and ca. 90
ns as measured by a logic analyzer on Gray Hawk Single.

Note that the BSP (predating upstream TDC support), uses a much simpler
method: for transfer rates >= 5 Mbps on R-Car Gen4, it enables TDC with
a hardcoded (hardware) TDCO value of 2 (i.e. actual 3), which matches
the behavior of this series at 8 Mbps.

Thanks for your comments!

[1] "[PATCH 0/9] can: rcar_canfd: Add support for Transceiver Delay Compensation"
    https://lore.kernel.org/cover.1748863848.git.geert+renesas@glider.be

[2] r8a77990.dtsi configures the CANFD core clock to 40 MHz, limiting
    transfer rates to 4 Mbps.  Enable support for 8 Mbps by adding to
    ebisu.dtsi:

	&canfd {
		assigned-clock-rates = <80000000>;
	}

    I plan to send patches to update this on all R-Car Gen3 and RZ/G2
    SoCs once this series has reached upstream.

Geert Uytterhoeven (10):
  can: rcar_canfd: Consistently use ndev for net_device pointers
  can: rcar_canfd: Remove bittiming debug prints
  can: rcar_canfd: Add helper variable ndev to rcar_canfd_rx_pkt()
  can: rcar_canfd: Add helper variable dev to
    rcar_canfd_reset_controller()
  can: rcar_canfd: Simplify data access in rcar_canfd_{ge,pu}t_data()
  can: rcar_canfd: Repurpose f_dcfg base for other registers
  can: rcar_canfd: Rename rcar_canfd_setrnc() to rcar_canfd_set_rnc()
  can: rcar_canfd: Share config code in rcar_canfd_set_bittiming()
  can: rcar_canfd: Return early in rcar_canfd_set_bittiming() when not
    FD
  can: rcar_canfd: Add support for Transceiver Delay Compensation

 drivers/net/can/rcar/rcar_canfd.c | 228 ++++++++++++++++++++----------
 1 file changed, 156 insertions(+), 72 deletions(-)

-- 
2.43.0

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds