Re: [PATCH 2/2] ath10k: search DT for qcom,ath10k-calibration-variant

Sven Eckelmann [off-list ref] writes:

Board Data File (BDF) is loaded upon driver boot-up procedure. The right
board data file is identified on QCA4019 using bus, bmi-chip-id and
bmi-board-id.

The problem, however, can occur when the (default) board data file cannot
fulfill with the vendor requirements and it is necessary to use a differe=

nt

board data file.

This problem was solved for SMBIOS by adding a special SMBIOS type 0xF8.
Something similar has to be provided for systems without SMBIOS but with
device trees. No solution was specified by QCA and therefore a new one ha=

s

to be found for ath10k.

The device tree requires addition strings to define the variant name

    wifi@a000000 {
    	status =3D "okay";
    	qcom,ath10k-calibration-variant =3D "RT-AC58U";
    };

    wifi@a800000 {
    	status =3D "okay";
    	qcom,ath10k-calibration-variant =3D "RT-AC58U";
    };

This would create the boarddata identifiers for the board-2.bin search

 *  bus=3Dahb,bmi-chip-id=3D0,bmi-board-id=3D16,variant=3DRT-AC58U
 *  bus=3Dahb,bmi-chip-id=3D0,bmi-board-id=3D17,variant=3DRT-AC58U

Signed-off-by: Sven Eckelmann <redacted>
---
Since RFC:

 - initialize variant pointer to have it initialized to NULL when
   of_property_read_string fails (thanks Christian Lamparter)
 - Only print warning that DT doesn't contain string ones (thanks Christi=

an

   Lamparter)
 - Split patch in DT doc and ath10k part (thanks Christian Lamparter)
 - Allow to overwrite the variant string via DT and ignore that SMBIOS ha=

d

   written anything to it

[...]

r)

 	return 0;
 }
=20
+static int ath10k_core_check_dt(struct ath10k *ar)
+{
+	struct device_node *node;
+	const char *variant =3D NULL;
+
+	node =3D ar->dev->of_node;
+	if (!node)
+		return -ENOENT;
+
+	of_property_read_string(node, "qcom,ath10k-calibration-variant",
+				&variant);
+	if (!variant)
+		return -ENODATA;
+
+	strscpy(ar->id.bdf_ext, variant, sizeof(ar->id.bdf_ext));

Kbuild bot found a warning here:

   drivers/net/wireless/ath/ath10k/core.c: In function 'ath10k_core_check_d=
t':

quoted

drivers/net/wireless/ath/ath10k/core.c:877:2: warning: ignoring return v=

alue of 'strscpy', declared with attribute warn_unused_result [-Wunused-res=
ult]
     strscpy(ar->id.bdf_ext, variant, sizeof(ar->id.bdf_ext));
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I guess warn_unused_result in strscpy() is a recent addition and that's
why you didn't see it.

--=20
Kalle Valo=