[PATCH v1 0/2] imx: mach: imx8: fdt: fix industrial GPU frequencies

[PATCH v1 0/2] imx: mach: imx8: fdt: fix industrial GPU frequencies

[Stefan Eichenberger]

On the industrial i.MX 8 variant, U-Boot limits the GPU clocks to
625 MHz by patching the device tree of the kernel. This series fixes two
issues with that code.

The first patch makes the helpers return the libfdt error codes, so
missing nodes are ignored again and real errors are printed with a
meaningful message. Before, booting a device tree without the GPU1
nodes printed a misleading error:

    Failed to set assigned-clock-rates for GPU1: FDT_ERR_BADPHANDLE

The second patch adds support for the GPU0 bus node name used by
mainline Linux and NXP downstream kernels starting with 6.18
(bus@53000000 instead of bus@53100000). Without it, GPU0 runs at the
default 700/850 MHz instead of the 625 MHz limit of the industrial SoC.

Stefan Eichenberger (2):
  imx: mach: imx8: fdt: return libfdt errors from helpers
  imx: mach: imx8: fdt: support newer GPU0 bus node name

 arch/arm/mach-imx/imx8/fdt.c | 35 +++++++++++++++--------------------
 1 file changed, 15 insertions(+), 20 deletions(-)

-- 
2.56.0

[PATCH v1 1/2] imx: mach: imx8: fdt: return libfdt errors from helpers

[Stefan Eichenberger]

From: Stefan Eichenberger <stefan.eichenberger@toradex.com>

delete_node() and change_property() replaced the libfdt error codes with
-ENXIO and -EINVAL, but the callers pass the result to fdt_strerror(),
which expects a libfdt error code. In addition,
update_fdt_gpu_industrial_frequencies() compared the result against the
positive ENXIO, so a missing node was reported as an error instead of
being ignored.

On an industrial i.MX 8 booted with a device tree that lacks the GPU1
nodes (e.g. mainline Linux), a misleading error is printed on every boot
because -ENXIO is interpreted by fdt_strerror() as a libfdt error code,
e.g.:

    Failed to set assigned-clock-rates for GPU1: FDT_ERR_BADPHANDLE

Return the libfdt error codes unchanged and ignore -FDT_ERR_NOTFOUND,
which fdt_path_offset() returns if the node does not exist.

Fixes: e9cf7f515a19 ("imx: mach: imx8: fdt: set correct frequencies for the industrial SoC")
Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
---
 arch/arm/mach-imx/imx8/fdt.c | 28 +++++++++-------------------
 1 file changed, 9 insertions(+), 19 deletions(-)

diff --git a/arch/arm/mach-imx/imx8/fdt.c b/arch/arm/mach-imx/imx8/fdt.c
index 8337edc2f62..630b5e55702 100644
--- a/arch/arm/mach-imx/imx8/fdt.c
+++ b/arch/arm/mach-imx/imx8/fdt.c
@@ -281,34 +281,24 @@ static int ft_add_optee_node(void *fdt, struct bd_info *bd)
 static int delete_node(void *blob, const char *node)
 {
 	int nodeoffset;
-	int err;
 
 	nodeoffset = fdt_path_offset(blob, node);
 	if (nodeoffset < 0)
-		return -ENXIO;
-
-	err = fdt_del_node(blob, nodeoffset);
-	if (err)
-		return -EINVAL;
+		return nodeoffset;
 
-	return 0;
+	return fdt_del_node(blob, nodeoffset);
 }
 
 static int change_property(void *blob, const char *node, const char *property,
 			   const void *value, int len)
 {
 	int nodeoffset;
-	int err;
 
 	nodeoffset = fdt_path_offset(blob, node);
 	if (nodeoffset < 0)
-		return -ENXIO;
-
-	err = fdt_setprop(blob, nodeoffset, property, value, len);
-	if (err)
-		return -EINVAL;
+		return nodeoffset;
 
-	return 0;
+	return fdt_setprop(blob, nodeoffset, property, value, len);
 }
 
 static void update_fdt_gpu_industrial_frequencies(void *blob)
@@ -330,21 +320,21 @@ static void update_fdt_gpu_industrial_frequencies(void *blob)
 	err = change_property(blob, "/bus@53100000/gpu@53100000",
 			      "assigned-clock-rates", gpu_assigned_clocks,
 			      sizeof(gpu_assigned_clocks));
-	if (err && err != ENXIO)
+	if (err && err != -FDT_ERR_NOTFOUND)
 		printf("Failed to set assigned-clock-rates for GPU0: %s\n",
 		       fdt_strerror(err));
 
 	err = change_property(blob, "/bus@54100000/gpu@54100000",
 			      "assigned-clock-rates", gpu_assigned_clocks,
 			      sizeof(gpu_assigned_clocks));
-	if (err && err != ENXIO)
+	if (err && err != -FDT_ERR_NOTFOUND)
 		printf("Failed to set assigned-clock-rates for GPU1: %s\n",
 		       fdt_strerror(err));
 
 	err = change_property(blob, "/bus@54100000/imx8_gpu1_ss@80000000",
 			      "operating-points", &gpu_opp_table,
 			      sizeof(gpu_opp_table));
-	if (err && err != ENXIO)
+	if (err && err != -FDT_ERR_NOTFOUND)
 		printf("Failed to set operating-points for GPU: %s\n",
 		       fdt_strerror(err));
 }
@@ -354,12 +344,12 @@ static void update_fdt_cpu_industrial_frequencies(void *blob)
 	int err;
 
 	err = delete_node(blob, "/opp-table-0/opp-1200000000");
-	if (err && err != -ENXIO)
+	if (err && err != -FDT_ERR_NOTFOUND)
 		printf("Failed to delete 1.2 GHz node on A53: %s\n",
 		       fdt_strerror(err));
 
 	err = delete_node(blob, "/opp-table-1/opp-1596000000");
-	if (err && err != -ENXIO)
+	if (err && err != -FDT_ERR_NOTFOUND)
 		printf("Failed to delete 1.596 GHz node on A72: %s\n",
 		       fdt_strerror(err));
 }
-- 
2.56.0

[PATCH v1 2/2] imx: mach: imx8: fdt: support newer GPU0 bus node name

[Stefan Eichenberger]

From: Stefan Eichenberger <stefan.eichenberger@toradex.com>

Mainline Linux and NXP downstream kernels starting with 6.18 name the
GPU0 subsystem bus@53000000, while older downstream kernels used
bus@53100000. Because of that, the industrial GPU clock rates were not
applied and GPU0 kept running at the default 700/850 MHz instead of
the 625 MHz limit of the industrial SoC.

Use /bus@53000000/gpu@53100000 and, if it does not exist, fall back to
the legacy /bus@53100000/gpu@53100000.

Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
---
 arch/arm/mach-imx/imx8/fdt.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-imx/imx8/fdt.c b/arch/arm/mach-imx/imx8/fdt.c
index 630b5e55702..05d2ddead91 100644
--- a/arch/arm/mach-imx/imx8/fdt.c
+++ b/arch/arm/mach-imx/imx8/fdt.c
@@ -317,9 +317,14 @@ static void update_fdt_gpu_industrial_frequencies(void *blob)
 	gpu_assigned_clocks[0] = cpu_to_fdt32(625000000); /* Core Clock */
 	gpu_assigned_clocks[1] = cpu_to_fdt32(625000000); /* Shader Clock */
 
-	err = change_property(blob, "/bus@53100000/gpu@53100000",
+	err = change_property(blob, "/bus@53000000/gpu@53100000",
 			      "assigned-clock-rates", gpu_assigned_clocks,
 			      sizeof(gpu_assigned_clocks));
+	/* NXP kernels before 6.18 use bus@53100000 */
+	if (err == -FDT_ERR_NOTFOUND)
+		err = change_property(blob, "/bus@53100000/gpu@53100000",
+				      "assigned-clock-rates", gpu_assigned_clocks,
+				      sizeof(gpu_assigned_clocks));
 	if (err && err != -FDT_ERR_NOTFOUND)
 		printf("Failed to set assigned-clock-rates for GPU0: %s\n",
 		       fdt_strerror(err));
-- 
2.56.0