Hello Geert,

I am sorry for the late reply.
Thank you for your feedback.

Subject: Re: [PATCH 1/3][can-next] can: rcar_can: Fix erroneous registration

Hi Fabrizio,

On Thu, Aug 23, 2018 at 3:08 PM Fabrizio Castro
[off-list ref] wrote:

quoted

Assigning 2 to "renesas,can-clock-select" tricks the driver into
registering the CAN interface, even though we don't want that.
This patch fixes this problem and also allows for architectures
missing some of the clocks (e.g. RZ/G2) to behave as expected.

I think the fix for the second issue is not needed (see my reply to the other
patch).

quoted

Fixes: 862e2b6af9413b43 ("can: rcar_can: support all input clocks")
Signed-off-by: Fabrizio Castro <redacted>
Signed-off-by: Chris Paterson <redacted>
---

This patch applies on linux-can-next-for-4.19-20180727

 drivers/net/can/rcar/rcar_can.c | 43 +++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/drivers/net/can/rcar/rcar_can.c b/drivers/net/can/rcar/rcar_can.c
index 11662f4..fbd9284 100644
--- a/drivers/net/can/rcar/rcar_can.c
+++ b/drivers/net/can/rcar/rcar_can.c

@@ -21,9 +21,13 @@
 #include <linux/clk.h>
 #include <linux/can/platform/rcar_can.h>
 #include <linux/of.h>
+#include <linux/of_device.h>

 #define RCAR_CAN_DRV_NAME      "rcar_can"

+#define RCAR_SUPPORTED_CLOCKS  (BIT(CLKR_CLKP1) | BIT(CLKR_CLKP2) | \
+                                BIT(CLKR_CLKEXT))
+
 /* Mailbox configuration:
  * mailbox 60 - 63 - Rx FIFO mailboxes
  * mailbox 56 - 59 - Tx FIFO mailboxes

@@ -745,10 +749,12 @@ static int rcar_can_probe(struct platform_device *pdev)
        u32 clock_select = CLKR_CLKP1;
        int err = -ENODEV;
        int irq;
+       uintptr_t allowed_clks = RCAR_SUPPORTED_CLOCKS;

        if (pdev->dev.of_node) {
                of_property_read_u32(pdev->dev.of_node,
                                     "renesas,can-clock-select", &clock_select);

quoted

+               allowed_clks = (uintptr_t)of_device_get_match_data(&pdev->dev);
        } else {
                pdata = dev_get_platdata(&pdev->dev);
                if (!pdata) {

@@ -789,7 +795,7 @@ static int rcar_can_probe(struct platform_device *pdev)
                goto fail_clk;
        }

-       if (clock_select >= ARRAY_SIZE(clock_names)) {
+       if (!(BIT(clock_select) & allowed_clks)) {

Hence you can just use RCAR_SUPPORTED_CLOCKS directly,
or better, just check clock_names[clock_select] != NULL, ...

I rather use RCAR_SUPPORTED_CLOCKS then, it's safer. I'll send a v2 for you to look at.

quoted

                err = -EINVAL;
                dev_err(&pdev->dev, "invalid CAN clock selected\n");
                goto fail_clk;

@@ -899,13 +905,34 @@ static int __maybe_unused rcar_can_resume(struct device *dev)
 static SIMPLE_DEV_PM_OPS(rcar_can_pm_ops, rcar_can_suspend, rcar_can_resume);

 static const struct of_device_id rcar_can_of_table[] __maybe_unused = {
-       { .compatible = "renesas,can-r8a7778" },
-       { .compatible = "renesas,can-r8a7779" },
-       { .compatible = "renesas,can-r8a7790" },
-       { .compatible = "renesas,can-r8a7791" },
-       { .compatible = "renesas,rcar-gen1-can" },
-       { .compatible = "renesas,rcar-gen2-can" },
-       { .compatible = "renesas,rcar-gen3-can" },
+       {
+               .compatible = "renesas,can-r8a7778",
+               .data = (void *)RCAR_SUPPORTED_CLOCKS,
+       },
+       {
+               .compatible = "renesas,can-r8a7779",
+               .data = (void *)RCAR_SUPPORTED_CLOCKS,
+       },
+       {
+               .compatible = "renesas,can-r8a7790",
+               .data = (void *)RCAR_SUPPORTED_CLOCKS,
+       },
+       {
+               .compatible = "renesas,can-r8a7791",
+               .data = (void *)RCAR_SUPPORTED_CLOCKS,
+       },
+       {
+               .compatible = "renesas,rcar-gen1-can",
+               .data = (void *)RCAR_SUPPORTED_CLOCKS,
+       },
+       {
+               .compatible = "renesas,rcar-gen2-can",
+               .data = (void *)RCAR_SUPPORTED_CLOCKS,
+       },
+       {
+               .compatible = "renesas,rcar-gen3-can",z
+               .data = (void *)RCAR_SUPPORTED_CLOCKS,
+       },
        { }

... and all of the above can dropped.

quoted

 };
 MODULE_DEVICE_TABLE(of, rcar_can_of_table);

BTW, why does the custom "renesas,can-clock-select" exist?
If guess the standard "assigned-clock-parents" wasn't suitable because there's
no actual defined clock for which you can change the parent?

Why do you need manual selection? Can't the driver just pick the most suitable
available clock, like other drivers (e.g. sh-sci) do?

Please have a look at 862e2b6af941 ("can: rcar_can: support all input clocks").
Maybe this could be improved in the future?

Thanks,
Fab

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

Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.