Re: [PATCH 3/3] reset: socfpga: add empty driver allowing consumers to probe

On Tue, 2021-10-05 at 13:12 +0200, Paweł Anikiel wrote:

On Tue, Oct 5, 2021 at 11:34 AM Philipp Zabel [off-list ref] wrote:

quoted

Hi Paweł,

On Mon, 2021-09-20 at 14:41 +0200, Paweł Anikiel wrote:

quoted

The early reset driver doesn't ever probe, which causes consuming
devices to be unable to probe. Add an empty driver to set this device
as available, allowing consumers to probe.

Signed-off-by: Paweł Anikiel <redacted>
---
 drivers/reset/reset-socfpga.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/reset/reset-socfpga.c b/drivers/reset/reset-socfpga.c
index 2a72f861f798..8c6492e5693c 100644
--- a/drivers/reset/reset-socfpga.c
+++ b/drivers/reset/reset-socfpga.c

@@ -92,3 +92,29 @@ void __init socfpga_reset_init(void)
      for_each_matching_node(np, socfpga_early_reset_dt_ids)
              a10_reset_init(np);
 }
+
+/*
+ * The early driver is problematic, because it doesn't register
+ * itself as a driver. This causes certain device links to prevent
+ * consumer devices from probing. The hacky solution is to register
+ * an empty driver, whose only job is to attach itself to the reset
+ * manager and call probe.
+ */
+static const struct of_device_id socfpga_reset_dt_ids[] = {
+     { .compatible = "altr,rst-mgr", },
+     { /* sentinel */ },
+};
+
+static int reset_simple_probe(struct platform_device *pdev)
+{
+     return 0;
+}
+
+static struct platform_driver reset_socfpga_driver = {
+     .probe  = reset_simple_probe,
+     .driver = {
+             .name           = "socfpga-reset",
+             .of_match_table = socfpga_reset_dt_ids,
+     },
+};
+builtin_platform_driver(reset_socfpga_driver);

If we can just let devlink delay all consumers until the empty driver is
probed, does the reset controller have to be registered early at all?

regards
Philipp

I asked Dinh if the reset controller code needs to be called early:

quoted

That's correct. It's for one of the SP timers.

Ah, right, those call of_reset_control_get() from TIMER_OF_DECLARE().
Thank you, I'll apply this to reset/fixes.

regards
Philipp

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