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1fee0c6131
Geert Uytterhoeven <geert+renesas@glider.be> says:
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 [1]:
- 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.
[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.
Link: https://patch.msgid.link/cover.1749655315.git.geert+renesas@glider.be
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
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Linux kernel
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