Re: [PATCH 01/32] of: Fix property supplier parsing

On Mon, Nov 9, 2020 at 11:45 AM Serge Semin [off-list ref] wrote:

Hello Andy,

On Mon, Nov 09, 2020 at 05:14:21PM +0200, Andy Shevchenko wrote:

quoted

On Sat, Nov 7, 2020 at 10:14 AM Damien Le Moal [off-list ref] wrote:

quoted

@@ -1308,7 +1308,6 @@ DEFINE_SIMPLE_PROP(pinctrl7, "pinctrl-7", NULL)
 DEFINE_SIMPLE_PROP(pinctrl8, "pinctrl-8", NULL)
 DEFINE_SUFFIX_PROP(regulators, "-supply", NULL)
 DEFINE_SUFFIX_PROP(gpio, "-gpio", "#gpio-cells")
-DEFINE_SUFFIX_PROP(gpios, "-gpios", "#gpio-cells")

Sorry, but the above doesn't sound right to me.
It's a generic code and you may imagine how many systems you broke by
this change.

Damien replaced the macro above with the code below (your removed it from your
message):

+static struct device_node *parse_gpios(struct device_node *np,
+                                      const char *prop_name, int index)
+{
+       /*
+        * Quirck for the DesignWare gpio-dwapb GPIO driver which defines
+        * the "snps,nr-gpios" property to indicate the total number of GPIOs
+        * available. As this conflict with "xx-gpios" reference properties,
+        * ignore it.
+        */
+       if (strcmp(prop_name, "snps,nr-gpios") == 0)
+               return NULL;
+
+       return parse_suffix_prop_cells(np, prop_name, index,
+                                      "-gpios", "#gpio-cells");
+}

So AFAICS removing the macro shouldn't cause any problem.

My concern was whether the quirk has been really needed. As I said the
"snps,nr-gpios" property has been marked as deprecated in favor of the standard
"ngpios" one. Due to the problem noted by Damien any deprecated property
utilization will cause the DW APB SSI DT-nodes probe malfunction. That
though implicitly but is supposed to encourage people to provide fixes for
the dts-files with the deprecated property replaced with "ngpios".

May be deprecated, but we've still got 53 cases in upstream dts files.
Plus changing doesn't work well for new DT with old kernels unless we
backport 'ngpios' support.

On the other hand an encouragement based on breaking the kernel doesn't seem a
good solution. So as I see it either we should accept the solution provided by
Damien, or replace it with a series of fixes for all dts-es with DW APB SSI
DT-node defined. I suggest to hear the OF-subsystem maintainers out what
solution would they prefer.

I'd suggest making failing to parse a warning rather than an error.
The devlink stuff is off by default anyways and is still changing.

Rob