RE: [PATCH v2 2/4] firmware: xilinx: Add version check for TRISTATE configuration

["Potthuri, Sai Krishna" <sai.krishna.potthuri@xxxxxxx>]

From: Shah, Tanmay <tanmay.shah@xxxxxxx> 
Sent: Monday, July 24, 2023 8:57 PM
To: Potthuri, Sai Krishna <sai.krishna.potthuri@xxxxxxx>; Linus Walleij <linus.walleij@xxxxxxxxxx>; Simek, Michal <michal.simek@xxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>; Krzysztof Kozlowski <krzysztof.kozlowski+dt@xxxxxxxxxx>; Conor Dooley <conor+dt@xxxxxxxxxx>; Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>; Levinsky, Ben <ben.levinsky@xxxxxxx>; Marek Vasut <marex@xxxxxxx>; Roman Gushchin <roman.gushchin@xxxxxxxxx>; Arnd Bergmann <arnd@xxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-gpio@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; saikrishna12468@xxxxxxxxx; git (AMD-Xilinx) <git@xxxxxxx>
Subject: Re: [PATCH v2 2/4] firmware: xilinx: Add version check for TRISTATE configuration


On 7/24/23 3:45 AM, Sai Krishna Potthuri wrote:
Support for configuring TRISTATE parameter is added in ZYNQMP PMUFW(Xilinx
ZynqMP Platform Management Firmware) Configuration Param Set version 2.0.
If the requested configuration is TRISTATE and platform is ZYNQMP then
check the version before requesting Xilinx firmware to set the
configuration.

Signed-off-by: Sai Krishna Potthuri mailto:sai.krishna.potthuri@xxxxxxx
---
 drivers/firmware/xilinx/zynqmp.c     | 9 +++++++++
 include/linux/firmware/xlnx-zynqmp.h | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
index f9498e7ea694..307717f24a98 100644
--- a/drivers/firmware/xilinx/zynqmp.c
+++ b/drivers/firmware/xilinx/zynqmp.c
@@ -1150,6 +1150,15 @@ EXPORT_SYMBOL_GPL(zynqmp_pm_pinctrl_get_config);
 int zynqmp_pm_pinctrl_set_config(const u32 pin, const u32 param,
 				 u32 value)
 {
+	int ret;
+
+	if (pm_family_code == ZYNQMP_FAMILY_CODE &&
+	    param == PM_PINCTRL_CONFIG_TRI_STATE) {
+		ret = zynqmp_pm_feature(PM_PINCTRL_CONFIG_PARAM_SET);
+		if (ret < PM_PINCTRL_PARAM_SET_VERSION)
+			return -EOPNOTSUPP;
Hi Sai,
If you get version 1 as response of feature_check then, it is possible to handle call as per old payload arguments?
something as following:
if (ret == 2) {
    //hanlde modified payload as per v2 of this call
} else if (ret == 1) {
    //handle original payload of this call as firmware is old.
} else {
    //fail here with -EOPNOTSUPP as we don't support this version.
} 
This way we can maintain backward compatibility with old firmware.

Hi Tanmay,

TRISTATE feature support added in version 2.0, hence we are checking the SET PARAM
version if the requested configuration is TRISTATE. If the version is 2.0 then we are
allowing the call otherwise will return error. This change will not impact the other
configurations and not impact the backward compatibility as we are checking the
version only for the TRISTATE configuration.

Regards
Sai Krishna


+	}
+
 	return zynqmp_pm_invoke_fn(PM_PINCTRL_CONFIG_PARAM_SET, pin,
 				   param, value, 0, NULL);
 }
diff --git a/include/linux/firmware/xlnx-zynqmp.h b/include/linux/firmware/xlnx-zynqmp.h
index d7f94b42ad4c..6359eeea8dd7 100644
--- a/include/linux/firmware/xlnx-zynqmp.h
+++ b/include/linux/firmware/xlnx-zynqmp.h
@@ -34,6 +34,8 @@
 /* PM API versions */
 #define PM_API_VERSION_2	2
 
+#define PM_PINCTRL_PARAM_SET_VERSION	2
+
 #define ZYNQMP_FAMILY_CODE 0x23
 #define VERSAL_FAMILY_CODE 0x26