Re: [PATCH v2 2/2] can: rcar_canfd: Fix page entries in the AFL list

Hi Biju,

On Fri, 7 Mar 2025 at 15:41, Geert Uytterhoeven geert@linux-m68k.org wrote:

On Thu, 20 Feb 2025 at 10:45, Biju Das biju.das.jz@bp.renesas.com wrote:

...

There are a total of 96 AFL pages and each page has 16 entries with registers CFDGAFLIDr, CFDGAFLMr, CFDGAFLP0r, CFDGAFLP1r holding the rule entries (r = 0..15).

Currently, RCANFD_GAFL* macros use a start variable to find AFL entries, which is incorrect as the testing on RZ/G3E shows ch1 and ch4 gets a start value of 0 and the register contents are overwritten.

Fix this issue by using rule_entry corresponding to the channel to find the page entries in the AFL list.

Fixes: dd3bd23eb438 ("can: rcar_canfd: Add Renesas R-Car CAN FD driver") Cc: stable@vger.kernel.org Signed-off-by: Biju Das biju.das.jz@bp.renesas.com

Thanks for your patch!

This finally fixes CAN2 and CAN3 on the White Hawk and White Hawk Single development boards based on R-Car V4H with 8 CAN channels (the transceivers for CAN4-7 are not mounted), so Tested-by: Geert Uytterhoeven geert+renesas@glider.be

Unfortunately, it does not fix CAN2 and CAN3 on the Gray Hawk Single development board, which is based on R-Car V4M with 4 CAN channels.

...

--- a/drivers/net/can/rcar/rcar_canfd.c +++ b/drivers/net/can/rcar/rcar_canfd.c @@ -787,10 +787,11 @@ static void rcar_canfd_configure_controller(struct rcar_canfd_global *gpriv) }

static void rcar_canfd_configure_afl_rules(struct rcar_canfd_global *gpriv,

•                                      u32 ch)
  

•                                      u32 ch, u32 rule_entry)
  

{ u32 cfg; int offset, start, page, num_rules = RCANFD_CHANNEL_NUMRULES;

•   u32 rule_entry_index = rule_entry % 16;
    u32 ridx = ch + RCANFD_RFFIFO_IDX;
  
    if (ch == 0) {
  

The out-of-context code does:

            start = 0; /* Channel 0 always starts from 0th rule */
    } else {
            /* Get number of Channel 0 rules and adjust */
            cfg = rcar_canfd_read(gpriv->base, RCANFD_GAFLCFG(ch));
            start = RCANFD_GAFLCFG_GETRNC(gpriv, 0, cfg);
    }

After your changes below, "start" is set but never used.

Looking at the actual behavior of your patch, the same can be achieved by updating start, by adding a single line here:

start += (ch & -2) * num_rules;

...

@@ -802,7 +803,7 @@ static void rcar_canfd_configure_afl_rules(struct rcar_canfd_global *gpriv, }

    /* Enable write access to entry */

•   page = RCANFD_GAFL_PAGENUM(start);
  

•   page = RCANFD_GAFL_PAGENUM(rule_entry);
  

The similar fix in the BSP[1] keeps the old value of start here. However, it does not make a difference for me (both R-Car V4H and V4M).

...

    rcar_canfd_set_bit(gpriv->base, RCANFD_GAFLECTR,
                       (RCANFD_GAFLECTR_AFLPN(gpriv, page) |
                        RCANFD_GAFLECTR_AFLDAE));

Gr{oetje,eeting}s,

Geert