gpu: nvgpu: add __must_check to gk20a_busy

The return value of gk20a_busy must be checked since it may not succeed
in some cases. Add the __must_check attribute that generates a compiler
warning for code that does not read the return value and fix all uses of
the function to take error cases into account.

Bug 200040921

Change-Id: Ibc2b119985fa230324c88026fe94fc5f1894fe4f
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: http://git-master/r/542552
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

drivers/gpu/nvgpu/gk20a/as_gk20a.c

@@ -82,8 +82,12 @@ int gk20a_as_release_share(struct gk20a_as_share *as_share)
 	if (atomic_dec_return(&as_share->ref_cnt) > 0)
 		return 0;
 
-	gk20a_busy(g->dev);
+	err = gk20a_busy(g->dev);
+	if (err)
+		return err;
+
 	err = gk20a_vm_release_share(as_share);
+
 	gk20a_idle(g->dev);
 
 	release_as_share_id(as_share->as, as_share->id);

drivers/gpu/nvgpu/gk20a/ctrl_gk20a.c

@@ -136,7 +136,7 @@ static int gk20a_ctrl_mark_compressible_write(
 		struct gk20a *g,
 		struct nvgpu_gpu_mark_compressible_write_args *args)
 {
-	int ret = 0;
+	int ret;
 
 	ret = gk20a_busy(g->dev);
 	if (ret)

drivers/gpu/nvgpu/gk20a/dbg_gpu_gk20a.c

@@ -571,7 +571,10 @@ static int dbg_set_powergate(struct dbg_session_gk20a *dbg_s,
 		    (g->dbg_powergating_disabled_refcount++ == 0)) {
 
 			gk20a_dbg(gpu_dbg_gpu_dbg | gpu_dbg_fn, "module busy");
-			gk20a_busy(g->dev);
+			err = gk20a_busy(g->dev);
+			if (err)
+				return err;
+
 			err = gk20a_busy(dbg_s->pdev);
 			if (err)
 				return -EPERM;

drivers/gpu/nvgpu/gk20a/debug_gk20a.c

@@ -166,9 +166,14 @@ void gk20a_debug_show_dump(struct platform_device *pdev,
 	struct gk20a *g = platform->g;
 	struct fifo_gk20a *f = &g->fifo;
 	u32 chid;
-	int i;
+	int i, err;
+
+	err = gk20a_busy(g->dev);
+	if (err) {
+		gk20a_debug_output(o, "failed to power on gpu: %d\n", err);
+		return;
+	}
 
-	gk20a_busy(g->dev);
 	for (i = 0; i < fifo_pbdma_status__size_1_v(); i++) {
 		u32 status = gk20a_readl(g, fifo_pbdma_status_r(i));
 		u32 chan_status = fifo_pbdma_status_chan_status_v(status);

drivers/gpu/nvgpu/gk20a/gk20a.h

@@ -703,7 +703,7 @@ void gk20a_create_sysfs(struct platform_device *dev);
 #define GK20A_SIM_IORESOURCE_MEM 2
 
 void gk20a_busy_noresume(struct platform_device *pdev);
-int gk20a_busy(struct platform_device *pdev);
+int __must_check gk20a_busy(struct platform_device *pdev);
 void gk20a_idle(struct platform_device *pdev);
 void gk20a_disable(struct gk20a *g, u32 units);
 void gk20a_enable(struct gk20a *g, u32 units);

drivers/gpu/nvgpu/gk20a/gk20a_sysfs.c

@@ -45,11 +45,15 @@ static ssize_t elcg_enable_store(struct device *device,
 	struct platform_device *ndev = to_platform_device(device);
 	struct gk20a *g = get_gk20a(ndev);
 	unsigned long val = 0;
+	int err;
 
 	if (kstrtoul(buf, 10, &val) < 0)
 		return -EINVAL;
 
-	gk20a_busy(g->dev);
+	err = gk20a_busy(g->dev);
+	if (err)
+		return err;
+
 	if (val) {
 		g->elcg_enabled = true;
 		gr_gk20a_init_elcg_mode(g, ELCG_AUTO, ENGINE_GR_GK20A);
@@ -84,6 +88,7 @@ static ssize_t blcg_enable_store(struct device *device,
 	struct platform_device *ndev = to_platform_device(device);
 	struct gk20a *g = get_gk20a(ndev);
 	unsigned long val = 0;
+	int err;
 
 	if (kstrtoul(buf, 10, &val) < 0)
 		return -EINVAL;
@@ -93,7 +98,10 @@ static ssize_t blcg_enable_store(struct device *device,
 	else
 		g->blcg_enabled = false;
 
-	gk20a_busy(g->dev);
+	err = gk20a_busy(g->dev);
+	if (err)
+		return err;
+
 	if (g->ops.clock_gating.blcg_bus_load_gating_prod)
 		g->ops.clock_gating.blcg_bus_load_gating_prod(g, g->blcg_enabled);
 	if (g->ops.clock_gating.blcg_ctxsw_firmware_load_gating_prod)
@@ -133,6 +141,7 @@ static ssize_t slcg_enable_store(struct device *device,
 	struct platform_device *ndev = to_platform_device(device);
 	struct gk20a *g = get_gk20a(ndev);
 	unsigned long val = 0;
+	int err;
 
 	if (kstrtoul(buf, 10, &val) < 0)
 		return -EINVAL;
@@ -147,7 +156,10 @@ static ssize_t slcg_enable_store(struct device *device,
 	 * init. Therefore, it would be incongruous to add it here. Once
 	 * it is added to init, we should add it here too.
 	 */
-	gk20a_busy(g->dev);
+	err = gk20a_busy(g->dev);
+	if (err)
+		return err;
+
 	if (g->ops.clock_gating.slcg_bus_load_gating_prod)
 		g->ops.clock_gating.slcg_bus_load_gating_prod(g, g->slcg_enabled);
 	if (g->ops.clock_gating.slcg_ce2_load_gating_prod)
@@ -305,11 +317,15 @@ static ssize_t gk20a_load_show(struct device *dev,
 	struct gk20a *g = get_gk20a(pdev);
 	u32 busy_time;
 	ssize_t res;
+	int err;
 
 	if (!g->power_on) {
 		busy_time = 0;
 	} else {
-		gk20a_busy(g->dev);
+		err = gk20a_busy(g->dev);
+		if (err)
+			return err;
+
 		gk20a_pmu_load_update(g);
 		gk20a_pmu_load_norm(g, &busy_time);
 		gk20a_idle(g->dev);
@@ -436,6 +452,9 @@ static ssize_t aelpg_enable_store(struct device *device,
 		return -EINVAL;
 
 	err = gk20a_busy(g->dev);
+	if (err)
+		return err;
+
 	if (g->pmu.pmu_ready) {
 		if (val && !g->aelpg_enabled) {
 			g->aelpg_enabled = true;

drivers/gpu/nvgpu/gk20a/pmu_gk20a.c

@@ -3721,13 +3721,12 @@ int gk20a_pmu_load_update(struct gk20a *g)
 void gk20a_pmu_get_load_counters(struct gk20a *g, u32 *busy_cycles,
 				 u32 *total_cycles)
 {
-	if (!g->power_on) {
+	if (!g->power_on || gk20a_busy(g->dev)) {
 		*busy_cycles = 0;
 		*total_cycles = 0;
 		return;
 	}
 
-	gk20a_busy(g->dev);
 	*busy_cycles = pwr_pmu_idle_count_value_v(
 		gk20a_readl(g, pwr_pmu_idle_count_r(1)));
 	rmb();
@@ -3740,10 +3739,9 @@ void gk20a_pmu_reset_load_counters(struct gk20a *g)
 {
 	u32 reg_val = pwr_pmu_idle_count_reset_f(1);
 
-	if (!g->power_on)
+	if (!g->power_on || gk20a_busy(g->dev))
 		return;
 
-	gk20a_busy(g->dev);
 	gk20a_writel(g, pwr_pmu_idle_count_r(2), reg_val);
 	wmb();
 	gk20a_writel(g, pwr_pmu_idle_count_r(1), reg_val);
@@ -3929,10 +3927,14 @@ static int elpg_residency_show(struct seq_file *s, void *data)
 	u32 ungating_time = 0;
 	u32 gating_cnt;
 	u64 total_ingating, total_ungating, residency, divisor, dividend;
+	int err;
 
 	/* Don't unnecessarily power on the device */
 	if (g->power_on) {
-		gk20a_busy(g->dev);
+		err = gk20a_busy(g->dev);
+		if (err)
+			return err;
+
 		gk20a_pmu_get_elpg_residency_gating(g, &ingating_time,
 			&ungating_time, &gating_cnt);
 		gk20a_idle(g->dev);
@@ -3974,9 +3976,13 @@ static int elpg_transitions_show(struct seq_file *s, void *data)
 	struct gk20a *g = s->private;
 	u32 ingating_time, ungating_time, total_gating_cnt;
 	u32 gating_cnt = 0;
+	int err;
 
 	if (g->power_on) {
-		gk20a_busy(g->dev);
+		err = gk20a_busy(g->dev);
+		if (err)
+			return err;
+
 		gk20a_pmu_get_elpg_residency_gating(g, &ingating_time,
 			&ungating_time, &gating_cnt);
 		gk20a_idle(g->dev);
@@ -4066,6 +4072,7 @@ static ssize_t perfmon_events_enable_write(struct file *file,
 	unsigned long val = 0;
 	char buf[40];
 	int buf_size;
+	int err;
 
 	memset(buf, 0, sizeof(buf));
 	buf_size = min(count, (sizeof(buf)-1));
@@ -4078,7 +4085,10 @@ static ssize_t perfmon_events_enable_write(struct file *file,
 
 	/* Don't turn on gk20a unnecessarily */
 	if (g->power_on) {
-		gk20a_busy(g->dev);
+		err = gk20a_busy(g->dev);
+		if (err)
+			return err;
+
 		if (val && !g->pmu.perfmon_sampling_enabled) {
 			g->pmu.perfmon_sampling_enabled = true;
 			pmu_perfmon_start_sampling(&(g->pmu));