Re: [PATCH v3 2/3] can: rcar_canfd: Add support for RZ/G2L family

Hi Geert,

Thank you for the review.

On Mon, Jul 26, 2021 at 10:53 AM Geert Uytterhoeven
[off-list ref] wrote:

Hi Prabhakar,

On Wed, Jul 21, 2021 at 9:50 PM Lad Prabhakar
[off-list ref] wrote:

quoted

CANFD block on RZ/G2L SoC is almost identical to one found on
R-Car Gen3 SoC's. On RZ/G2L SoC interrupt sources for each channel
are split into different sources and the IP doesn't divide (1/2)
CANFD clock within the IP.

This patch adds compatible string for RZ/G2L family and registers
the irq handlers required for CANFD operation. IRQ numbers are now
fetched based on names instead of indices. For backward compatibility
on non RZ/G2L SoC's we fallback reading based on indices.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

Thanks for the update!

I think you misunderstood my comment on v1 about the interrupt
handlers, cfr. below.

Argh my bad I took it the other way round!

quoted

--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c

quoted

@@ -1577,6 +1586,53 @@ static int rcar_canfd_channel_probe(struct rcar_canfd_global *gpriv, u32 ch,
        priv->can.clock.freq = fcan_freq;
        dev_info(&pdev->dev, "can_clk rate is %u\n", priv->can.clock.freq);

+       if (gpriv->chip_id == RENESAS_RZG2L) {
+               char *irq_name;
+               int err_irq;
+               int tx_irq;
+
+               err_irq = platform_get_irq_byname(pdev, ch == 0 ? "ch0_err" : "ch1_err");
+               if (err_irq < 0) {
+                       err = err_irq;
+                       goto fail;
+               }
+
+               tx_irq = platform_get_irq_byname(pdev, ch == 0 ? "ch0_trx" : "ch1_trx");
+               if (tx_irq < 0) {
+                       err = tx_irq;
+                       goto fail;
+               }
+
+               irq_name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+                                         "canfd.ch%d_err", ch);
+               if (!irq_name) {
+                       err = -ENOMEM;
+                       goto fail;
+               }
+               err = devm_request_irq(&pdev->dev, err_irq,
+                                      rcar_canfd_channel_interrupt, 0,

This is the same interrupt handler...

quoted

+                                      irq_name, gpriv);
+               if (err) {
+                       dev_err(&pdev->dev, "devm_request_irq CH Err(%d) failed, error %d\n",
+                               err_irq, err);
+                       goto fail;
+               }
+               irq_name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+                                         "canfd.ch%d_trx", ch);
+               if (!irq_name) {
+                       err = -ENOMEM;
+                       goto fail;
+               }
+               err = devm_request_irq(&pdev->dev, tx_irq,
+                                      rcar_canfd_channel_interrupt, 0,

... as this one.

quoted

+                                      irq_name, gpriv);
+               if (err) {
+                       dev_err(&pdev->dev, "devm_request_irq Tx (%d) failed, error %d\n",
+                               tx_irq, err);
+                       goto fail;
+               }
+       }
+
        if (gpriv->fdmode) {
                priv->can.bittiming_const = &rcar_canfd_nom_bittiming_const;
                priv->can.data_bittiming_const =

quoted

@@ -1711,20 +1798,51 @@ static int rcar_canfd_probe(struct platform_device *pdev)
        gpriv->base = addr;

        /* Request IRQ that's common for both channels */
-       err = devm_request_irq(&pdev->dev, ch_irq,
-                              rcar_canfd_channel_interrupt, 0,
-                              "canfd.chn", gpriv);
-       if (err) {
-               dev_err(&pdev->dev, "devm_request_irq(%d) failed, error %d\n",
-                       ch_irq, err);
-               goto fail_dev;
+       if (gpriv->chip_id == RENESAS_RCAR_GEN3) {
+               err = devm_request_irq(&pdev->dev, ch_irq,
+                                      rcar_canfd_channel_interrupt, 0,
+                                      "canfd.ch_int", gpriv);
+               if (err) {
+                       dev_err(&pdev->dev, "devm_request_irq(%d) failed, error %d\n",
+                               ch_irq, err);
+                       goto fail_dev;
+               }
+
+               err = devm_request_irq(&pdev->dev, g_irq,
+                                      rcar_canfd_global_interrupt, 0,
+                                      "canfd.g_int", gpriv);
+               if (err) {
+                       dev_err(&pdev->dev, "devm_request_irq(%d) failed, error %d\n",
+                               g_irq, err);
+                       goto fail_dev;
+               }
+       } else {
+               err = devm_request_irq(&pdev->dev, g_recc_irq,
+                                      rcar_canfd_global_interrupt, 0,

This is the same interrupt handler...

quoted

+                                      "canfd.g_recc", gpriv);
+
+               if (err) {
+                       dev_err(&pdev->dev, "devm_request_irq(%d) failed, error %d\n",
+                               g_recc_irq, err);
+                       goto fail_dev;
+               }
+
+               err = devm_request_irq(&pdev->dev, g_err_irq,
+                                      rcar_canfd_global_interrupt, 0,

... as this one.

quoted

+                                      "canfd.g_err", gpriv);
+               if (err) {
+                       dev_err(&pdev->dev, "devm_request_irq(%d) failed, error %d\n",
+                               g_err_irq, err);
+                       goto fail_dev;
+               }
        }
-       err = devm_request_irq(&pdev->dev, g_irq,
-                              rcar_canfd_global_interrupt, 0,
-                              "canfd.gbl", gpriv);
+
+       err = reset_control_reset(gpriv->rstc1);
+       if (err)
+               goto fail_dev;
+       err = reset_control_reset(gpriv->rstc2);
        if (err) {
-               dev_err(&pdev->dev, "devm_request_irq(%d) failed, error %d\n",
-                       g_irq, err);
+               reset_control_assert(gpriv->rstc1);
                goto fail_dev;
        }

I did not object to having fine-grained interrupt handlers on RZ/G2L.
I did object to duplicating code in global and fine-grained interrupt
handlers.

The trick to have both is to let the global interrupt handlers call
(conditionally) into the fine-grained handlers. In pseudo-code:

    global_interrupt_handler()
    {
            if (...)
                    fine_grained_handler1();

            if (...)
                    fine_grained_handler2();
            ...
    }

On R-Car Gen3, you register the global interrupt handlers, as before.
On RZ/G2L, you register the fine-grained interrupt handlers instead.

Agreed will re-spin with the fine-grained version tomorrow.

Cheers,
Prabhakar

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