platform/x86/amd/pmf: Fix clang unused variable warning

variable 'mode' is used uninitialized whenever switch default is taken
in sps.c which leads to the following clang warning.

drivers/platform/x86/amd/pmf/sps.c:96:2: error: variable 'mode' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
          default:
          ^~~~~~~
  drivers/platform/x86/amd/pmf/sps.c:101:9: note: uninitialized use occurs here
          return mode;
                 ^~~~
  drivers/platform/x86/amd/pmf/sps.c:84:9: note: initialize the variable 'mode' to silence this warning
          u8 mode;
                 ^
                  = '\0'
  1 error generated.

Fix it by returning -EOPNOTSUPP in default case and also change the return
type of the function amd_pmf_get_pprof_modes() to keep it similar like
other drivers which implement platform_profile.

Fixes: 4c71ae4144 ("platform/x86/amd/pmf: Add support SPS PMF feature")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20220822062917.4061503-1-Shyam-sundar.S-k@amd.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/amd/pmf/auto-mode.c

@@ -264,7 +264,7 @@ static void amd_pmf_load_defaults_auto_mode(struct amd_pmf_dev *dev)
 	dev->socket_power_history_idx = -1;
 }
 
-void amd_pmf_reset_amt(struct amd_pmf_dev *dev)
+int amd_pmf_reset_amt(struct amd_pmf_dev *dev)
 {
 	/*
 	 * OEM BIOS implementation guide says that if the auto mode is enabled
@@ -275,11 +275,15 @@ void amd_pmf_reset_amt(struct amd_pmf_dev *dev)
 	 */
 
 	if (is_apmf_func_supported(dev, APMF_FUNC_STATIC_SLIDER_GRANULAR)) {
-		u8 mode = amd_pmf_get_pprof_modes(dev);
+		int mode = amd_pmf_get_pprof_modes(dev);
+
+		if (mode < 0)
+			return mode;
 
 		dev_dbg(dev->dev, "resetting AMT thermals\n");
 		amd_pmf_update_slider(dev, SLIDER_OP_SET, mode, NULL);
 	}
+	return 0;
 }
 
 void amd_pmf_handle_amt(struct amd_pmf_dev *dev)

drivers/platform/x86/amd/pmf/core.c

@@ -65,6 +65,9 @@ static int current_power_limits_show(struct seq_file *seq, void *unused)
 	int mode, src = 0;
 
 	mode = amd_pmf_get_pprof_modes(dev);
+	if (mode < 0)
+		return mode;
+
 	src = amd_pmf_get_power_source();
 	amd_pmf_update_slider(dev, SLIDER_OP_GET, mode, &table);
 	seq_printf(seq, "spl:%u fppt:%u sppt:%u sppt_apu_only:%u stt_min:%u stt[APU]:%u stt[HS2]: %u\n",

drivers/platform/x86/amd/pmf/pmf.h

@@ -303,7 +303,7 @@ int amd_pmf_init_metrics_table(struct amd_pmf_dev *dev);
 int amd_pmf_get_power_source(void);
 
 /* SPS Layer */
-u8 amd_pmf_get_pprof_modes(struct amd_pmf_dev *pmf);
+int amd_pmf_get_pprof_modes(struct amd_pmf_dev *pmf);
 void amd_pmf_update_slider(struct amd_pmf_dev *dev, bool op, int idx,
 			   struct amd_pmf_static_slider_granular *table);
 int amd_pmf_init_sps(struct amd_pmf_dev *dev);
@@ -322,6 +322,6 @@ void amd_pmf_trans_automode(struct amd_pmf_dev *dev, int socket_power, ktime_t t
 int apmf_get_sbios_requests(struct amd_pmf_dev *pdev, struct apmf_sbios_req *req);
 
 void amd_pmf_update_2_cql(struct amd_pmf_dev *dev, bool is_cql_event);
-void amd_pmf_reset_amt(struct amd_pmf_dev *dev);
+int amd_pmf_reset_amt(struct amd_pmf_dev *dev);
 void amd_pmf_handle_amt(struct amd_pmf_dev *dev);
 #endif /* PMF_H */

drivers/platform/x86/amd/pmf/sps.c

@@ -79,9 +79,9 @@ static int amd_pmf_profile_get(struct platform_profile_handler *pprof,
 	return 0;
 }
 
-u8 amd_pmf_get_pprof_modes(struct amd_pmf_dev *pmf)
+int amd_pmf_get_pprof_modes(struct amd_pmf_dev *pmf)
 {
-	u8 mode;
+	int mode;
 
 	switch (pmf->current_profile) {
 	case PLATFORM_PROFILE_PERFORMANCE:
@@ -95,7 +95,7 @@ u8 amd_pmf_get_pprof_modes(struct amd_pmf_dev *pmf)
 		break;
 	default:
 		dev_err(pmf->dev, "Unknown Platform Profile.\n");
-		break;
+		return -EOPNOTSUPP;
 	}
 
 	return mode;
@@ -105,10 +105,13 @@ static int amd_pmf_profile_set(struct platform_profile_handler *pprof,
 			       enum platform_profile_option profile)
 {
 	struct amd_pmf_dev *pmf = container_of(pprof, struct amd_pmf_dev, pprof);
-	u8 mode;
+	int mode;
 
 	pmf->current_profile = profile;
 	mode = amd_pmf_get_pprof_modes(pmf);
+	if (mode < 0)
+		return mode;
+
 	amd_pmf_update_slider(pmf, SLIDER_OP_SET, mode, NULL);
 	return 0;
 }