[RFC PATCH 0/2] drm/amd/display: switch amdgpu_dm_connector to

[RFC PATCH 0/2] drm/amd/display: switch amdgpu_dm_connector to

[Melissa Wen]

Hi,

I'm debugging a null-pointer dereference when running
igt@kms_connector_force_edid and the way I found to solve the bug is to
stop using raw edid handler in amdgpu_connector_funcs_force and
create_eml_sink in favor of managing resouces via sruct drm_edid helpers
(Patch 1). The proper solution seems to be switch amdgpu_dm_connector
from struct edid to struct drm_edid and avoid the usage of different
approaches in the driver (Patch 2). However, doing it implies a good
amount of work and validation, therefore I decided to send this RFC
first to collect opinions and check if there is any parallel work on
this side. It's a working in progress.

The null-pointer error trigger by the igt@kms_connector_force_edid test
was introduced by:
- e54ed41620f ("drm/amd/display: Remove unwanted drm edid references")

You can check the error trace in the first patch.

This series was tested with kms_hdmi_inject and kms_force_connector. No
null-pointer error, kms_hdmi_inject is successul and kms_force_connector
is sucessful after the second execution - the force-edid subtest
still fails in the first run (I'm still investigating).

There is also a couple of cast warnings to be addressed - I'm looking
for the best replacement. 

I appreciate any feedback and testing.

Melissa

Melissa Wen (2):
  drm/amd/display: fix null-pointer dereference on edid reading
  drm/amd/display: switch amdgpu_dm_connector to use struct drm_edid

 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 78 ++++++++++---------
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  4 +-
 .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  9 ++-
 .../display/amdgpu_dm/amdgpu_dm_mst_types.c   | 23 +++---
 4 files changed, 60 insertions(+), 54 deletions(-)

-- 
2.43.0

[RFC PATCH 1/2] drm/amd/display: fix null-pointer dereference on edid reading

[Melissa Wen]

Use drm_edid helpers to fix a null-pointer derefence that happens when
running igt@kms_force_connector_basic in a system with DCN2.1 and HDMI
connector detected as below:

[  +0.178146] BUG: kernel NULL pointer dereference, address: 00000000000004c0
[  +0.000010] #PF: supervisor read access in kernel mode
[  +0.000005] #PF: error_code(0x0000) - not-present page
[  +0.000004] PGD 0 P4D 0
[  +0.000006] Oops: 0000 [#1] PREEMPT SMP NOPTI
[  +0.000006] CPU: 15 PID: 2368 Comm: kms_force_conne Not tainted 6.5.0-asdn+ #152
[  +0.000005] Hardware name: HP HP ENVY x360 Convertible 13-ay1xxx/8929, BIOS F.01 07/14/2021
[  +0.000004] RIP: 0010:i2c_transfer+0xd/0x100
[  +0.000011] Code: ea fc ff ff 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 41 54 55 53 <48> 8b 47 10 48 89 fb 48 83 38 00 0f 84 b3 00 00 00 83 3d 2f 80 16
[  +0.000004] RSP: 0018:ffff9c4f89c0fad0 EFLAGS: 00010246
[  +0.000005] RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000000080
[  +0.000003] RDX: 0000000000000002 RSI: ffff9c4f89c0fb20 RDI: 00000000000004b0
[  +0.000003] RBP: ffff9c4f89c0fb80 R08: 0000000000000080 R09: ffff8d8e0b15b980
[  +0.000003] R10: 00000000000380e0 R11: 0000000000000000 R12: 0000000000000080
[  +0.000002] R13: 0000000000000002 R14: ffff9c4f89c0fb0e R15: ffff9c4f89c0fb0f
[  +0.000004] FS:  00007f9ad2176c40(0000) GS:ffff8d90fe9c0000(0000) knlGS:0000000000000000
[  +0.000003] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  +0.000004] CR2: 00000000000004c0 CR3: 0000000121bc4000 CR4: 0000000000750ee0
[  +0.000003] PKRU: 55555554
[  +0.000003] Call Trace:
[  +0.000006]  <TASK>
[  +0.000006]  ? __die+0x23/0x70
[  +0.000011]  ? page_fault_oops+0x17d/0x4c0
[  +0.000008]  ? preempt_count_add+0x6e/0xa0
[  +0.000008]  ? srso_alias_return_thunk+0x5/0x7f
[  +0.000011]  ? exc_page_fault+0x7f/0x180
[  +0.000009]  ? asm_exc_page_fault+0x26/0x30
[  +0.000013]  ? i2c_transfer+0xd/0x100
[  +0.000010]  drm_do_probe_ddc_edid+0xc2/0x140 [drm]
[  +0.000067]  ? srso_alias_return_thunk+0x5/0x7f
[  +0.000006]  ? _drm_do_get_edid+0x97/0x3c0 [drm]
[  +0.000043]  ? __pfx_drm_do_probe_ddc_edid+0x10/0x10 [drm]
[  +0.000042]  edid_block_read+0x3b/0xd0 [drm]
[  +0.000043]  _drm_do_get_edid+0xb6/0x3c0 [drm]
[  +0.000041]  ? __pfx_drm_do_probe_ddc_edid+0x10/0x10 [drm]
[  +0.000043]  drm_edid_read_custom+0x37/0xd0 [drm]
[  +0.000044]  amdgpu_dm_connector_mode_valid+0x129/0x1d0 [amdgpu]
[  +0.000153]  drm_connector_mode_valid+0x3b/0x60 [drm_kms_helper]
[  +0.000000]  __drm_helper_update_and_validate+0xfe/0x3c0 [drm_kms_helper]
[  +0.000000]  ? amdgpu_dm_connector_get_modes+0xb6/0x520 [amdgpu]
[  +0.000000]  ? srso_alias_return_thunk+0x5/0x7f
[  +0.000000]  drm_helper_probe_single_connector_modes+0x2ab/0x540 [drm_kms_helper]
[  +0.000000]  status_store+0xb2/0x1f0 [drm]
[  +0.000000]  kernfs_fop_write_iter+0x136/0x1d0
[  +0.000000]  vfs_write+0x24d/0x440
[  +0.000000]  ksys_write+0x6f/0xf0
[  +0.000000]  do_syscall_64+0x60/0xc0
[  +0.000000]  ? srso_alias_return_thunk+0x5/0x7f
[  +0.000000]  ? syscall_exit_to_user_mode+0x2b/0x40
[  +0.000000]  ? srso_alias_return_thunk+0x5/0x7f
[  +0.000000]  ? do_syscall_64+0x6c/0xc0
[  +0.000000]  ? do_syscall_64+0x6c/0xc0
[  +0.000000]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[  +0.000000] RIP: 0033:0x7f9ad46b4b00
[  +0.000000] Code: 40 00 48 8b 15 19 b3 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 80 3d e1 3a 0e 00 00 74 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 48 83 ec 28 48 89
[  +0.000000] RSP: 002b:00007ffcbd3bd6d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
[  +0.000000] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9ad46b4b00
[  +0.000000] RDX: 0000000000000002 RSI: 00007f9ad48a7417 RDI: 0000000000000009
[  +0.000000] RBP: 0000000000000002 R08: 0000000000000064 R09: 0000000000000000
[  +0.000000] R10: 0000000000000000 R11: 0000000000000202 R12: 00007f9ad48a7417
[  +0.000000] R13: 0000000000000009 R14: 00007ffcbd3bd760 R15: 0000000000000001
[  +0.000000]  </TASK>
[  +0.000000] Modules linked in: ctr ccm rfcomm snd_seq_dummy snd_hrtimer snd_seq snd_seq_device cmac algif_hash algif_skcipher af_alg bnep btusb btrtl btbcm btintel btmtk bluetooth uvcvideo videobuf2_vmalloc sha3_generic videobuf2_memops uvc jitterentropy_rng videobuf2_v4l2 videodev drbg videobuf2_common ansi_cprng mc ecdh_generic ecc qrtr binfmt_misc hid_sensor_accel_3d hid_sensor_magn_3d hid_sensor_gyro_3d hid_sensor_trigger industrialio_triggered_buffer kfifo_buf industrialio snd_ctl_led joydev hid_sensor_iio_common rtw89_8852ae rtw89_8852a rtw89_pci snd_hda_codec_realtek rtw89_core snd_hda_codec_generic intel_rapl_msr ledtrig_audio intel_rapl_common snd_hda_codec_hdmi mac80211 snd_hda_intel snd_intel_dspcfg kvm_amd snd_hda_codec snd_soc_dmic snd_acp3x_rn snd_acp3x_pdm_dma libarc4 snd_hwdep snd_soc_core kvm snd_hda_core cfg80211 snd_pci_acp6x snd_pcm nls_ascii snd_timer hp_wmi snd_pci_acp5x nls_cp437 snd_rn_pci_acp3x ucsi_acpi sparse_keymap ccp snd platform_profile snd_acp_config typec_ucsi irqbypass vfat sp5100_tco
[  +0.000000]  snd_soc_acpi fat rapl pcspkr wmi_bmof roles rfkill rng_core snd_pci_acp3x soundcore k10temp watchdog typec battery ac amd_pmc acpi_tad button hid_sensor_hub hid_multitouch evdev serio_raw msr parport_pc ppdev lp parport fuse loop efi_pstore configfs ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 btrfs blake2b_generic dm_crypt dm_mod efivarfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx libcrc32c crc32c_generic xor raid6_pq raid1 raid0 multipath linear md_mod amdgpu amdxcp i2c_algo_bit drm_ttm_helper ttm crc32_pclmul crc32c_intel drm_exec gpu_sched drm_suballoc_helper nvme ghash_clmulni_intel drm_buddy drm_display_helper sha512_ssse3 nvme_core ahci xhci_pci sha512_generic hid_generic xhci_hcd libahci rtsx_pci_sdmmc t10_pi i2c_hid_acpi drm_kms_helper i2c_hid mmc_core libata aesni_intel crc64_rocksoft_generic crypto_simd amd_sfh crc64_rocksoft scsi_mod usbcore cryptd crc_t10dif cec drm crct10dif_generic hid rtsx_pci crct10dif_pclmul scsi_common rc_core crc64 i2c_piix4
[  +0.000000]  usb_common crct10dif_common video wmi
[  +0.000000] CR2: 00000000000004c0
[  +0.000000] ---[ end trace 0000000000000000 ]---

Fixes: e54ed41620f ("drm/amd/display: Remove unwanted drm edid references")
Signed-off-by: Melissa Wen <mwen@igalia.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 23 +++++++++++--------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index cd98b3565178..68e71e2ea472 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6561,10 +6561,10 @@ amdgpu_dm_connector_late_register(struct drm_connector *connector)
 static void amdgpu_dm_connector_funcs_force(struct drm_connector *connector)
 {
 	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
-	struct amdgpu_connector *amdgpu_connector = to_amdgpu_connector(connector);
 	struct dc_link *dc_link = aconnector->dc_link;
 	struct dc_sink *dc_em_sink = aconnector->dc_em_sink;
-	struct edid *edid;
+	const struct drm_edid *drm_edid;
+	const struct edid *edid;
 
 	/*
 	 * Note: drm_get_edid gets edid in the following order:
@@ -6572,18 +6572,19 @@ static void amdgpu_dm_connector_funcs_force(struct drm_connector *connector)
 	 * 2) firmware EDID if set via edid_firmware module parameter
 	 * 3) regular DDC read.
 	 */
-	edid = drm_get_edid(connector, &amdgpu_connector->ddc_bus->aux.ddc);
-	if (!edid) {
+	drm_edid = drm_edid_read(connector);
+
+	if (!drm_edid) {
 		DRM_ERROR("No EDID found on connector: %s.\n", connector->name);
 		return;
 	}
-
+	edid = drm_edid_raw(drm_edid);
 	aconnector->edid = edid;
 
 	/* Update emulated (virtual) sink's EDID */
 	if (dc_em_sink && dc_link) {
 		memset(&dc_em_sink->edid_caps, 0, sizeof(struct dc_edid_caps));
-		memmove(dc_em_sink->dc_edid.raw_edid, edid, (edid->extensions + 1) * EDID_LENGTH);
+		memmove(dc_em_sink->dc_edid.raw_edid, (uint8_t *)edid, (edid->extensions + 1) * EDID_LENGTH);
 		dm_helpers_parse_edid_caps(
 			dc_link,
 			&dc_em_sink->dc_edid,
@@ -6613,12 +6614,12 @@ static int get_modes(struct drm_connector *connector)
 static void create_eml_sink(struct amdgpu_dm_connector *aconnector)
 {
 	struct drm_connector *connector = &aconnector->base;
-	struct amdgpu_connector *amdgpu_connector = to_amdgpu_connector(&aconnector->base);
 	struct dc_sink_init_data init_params = {
 			.link = aconnector->dc_link,
 			.sink_signal = SIGNAL_TYPE_VIRTUAL
 	};
-	struct edid *edid;
+	const struct drm_edid *drm_edid;
+	const struct edid *edid;
 
 	/*
 	 * Note: drm_get_edid gets edid in the following order:
@@ -6626,12 +6627,14 @@ static void create_eml_sink(struct amdgpu_dm_connector *aconnector)
 	 * 2) firmware EDID if set via edid_firmware module parameter
 	 * 3) regular DDC read.
 	 */
-	edid = drm_get_edid(connector, &amdgpu_connector->ddc_bus->aux.ddc);
-	if (!edid) {
+	drm_edid = drm_edid_read(connector);
+	if (!drm_edid) {
 		DRM_ERROR("No EDID found on connector: %s.\n", connector->name);
 		return;
 	}
 
+	edid = drm_edid_raw(drm_edid);
+
 	if (drm_detect_hdmi_monitor(edid))
 		init_params.sink_signal = SIGNAL_TYPE_HDMI_TYPE_A;
 
-- 
2.43.0

[RFC PATCH 2/2] drm/amd/display: switch amdgpu_dm_connector to use struct drm_edid

[Melissa Wen]

Replace raw edid handling (struct edid) with the opaque EDID type
(struct drm_edid) on amdgpu_dm_connector for consistency. It may also
prevent mismatch of approaches in different parts of the driver code.
Working in progress. There are a couple of cast warnings and it was only
tested with IGT.

Signed-off-by: Melissa Wen <mwen@igalia.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 63 ++++++++++---------
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  4 +-
 .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  9 +--
 .../display/amdgpu_dm/amdgpu_dm_mst_types.c   | 23 +++----
 4 files changed, 51 insertions(+), 48 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 68e71e2ea472..741081d73bb3 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -3277,12 +3277,12 @@ void amdgpu_dm_update_connector_after_detect(
 					&aconnector->dm_dp_aux.aux);
 			}
 		} else {
-			aconnector->edid =
-				(struct edid *)sink->dc_edid.raw_edid;
+			const struct edid *edid = (const struct edid *)sink->dc_edid.raw_edid;
+			aconnector->edid = drm_edid_alloc(edid, (edid->extensions + 1) * EDID_LENGTH);
 
 			if (aconnector->dc_link->aux_mode)
 				drm_dp_cec_set_edid(&aconnector->dm_dp_aux.aux,
-						    aconnector->edid);
+						    drm_edid_raw(aconnector->edid));
 		}
 
 		if (!aconnector->timing_requested) {
@@ -3293,13 +3293,13 @@ void amdgpu_dm_update_connector_after_detect(
 					"failed to create aconnector->requested_timing\n");
 		}
 
-		drm_connector_update_edid_property(connector, aconnector->edid);
+		drm_edid_connector_update(connector, aconnector->edid);
 		amdgpu_dm_update_freesync_caps(connector, aconnector->edid);
 		update_connector_ext_caps(aconnector);
 	} else {
 		drm_dp_cec_unset_edid(&aconnector->dm_dp_aux.aux);
 		amdgpu_dm_update_freesync_caps(connector, NULL);
-		drm_connector_update_edid_property(connector, NULL);
+		drm_edid_connector_update(connector, NULL);
 		aconnector->num_modes = 0;
 		dc_sink_release(aconnector->dc_sink);
 		aconnector->dc_sink = NULL;
@@ -6564,7 +6564,6 @@ static void amdgpu_dm_connector_funcs_force(struct drm_connector *connector)
 	struct dc_link *dc_link = aconnector->dc_link;
 	struct dc_sink *dc_em_sink = aconnector->dc_em_sink;
 	const struct drm_edid *drm_edid;
-	const struct edid *edid;
 
 	/*
 	 * Note: drm_get_edid gets edid in the following order:
@@ -6578,11 +6577,12 @@ static void amdgpu_dm_connector_funcs_force(struct drm_connector *connector)
 		DRM_ERROR("No EDID found on connector: %s.\n", connector->name);
 		return;
 	}
-	edid = drm_edid_raw(drm_edid);
-	aconnector->edid = edid;
-
+	aconnector->edid = drm_edid;
+	drm_edid_connector_update(connector, drm_edid);
 	/* Update emulated (virtual) sink's EDID */
 	if (dc_em_sink && dc_link) {
+		const struct edid *edid = drm_edid_raw(drm_edid);
+
 		memset(&dc_em_sink->edid_caps, 0, sizeof(struct dc_edid_caps));
 		memmove(dc_em_sink->dc_edid.raw_edid, (uint8_t *)edid, (edid->extensions + 1) * EDID_LENGTH);
 		dm_helpers_parse_edid_caps(
@@ -6633,13 +6633,13 @@ static void create_eml_sink(struct amdgpu_dm_connector *aconnector)
 		return;
 	}
 
-	edid = drm_edid_raw(drm_edid);
-
-	if (drm_detect_hdmi_monitor(edid))
+	if (connector->display_info.is_hdmi)
 		init_params.sink_signal = SIGNAL_TYPE_HDMI_TYPE_A;
 
-	aconnector->edid = edid;
+	aconnector->edid = drm_edid;
+	drm_edid_connector_update(connector, drm_edid);
 
+	edid = drm_edid_raw(drm_edid);
 	aconnector->dc_em_sink = dc_link_add_remote_sink(
 		aconnector->dc_link,
 		(uint8_t *)edid,
@@ -7322,16 +7322,16 @@ static void amdgpu_set_panel_orientation(struct drm_connector *connector)
 }
 
 static void amdgpu_dm_connector_ddc_get_modes(struct drm_connector *connector,
-					      struct edid *edid)
+					      const struct drm_edid *drm_edid)
 {
 	struct amdgpu_dm_connector *amdgpu_dm_connector =
 			to_amdgpu_dm_connector(connector);
 
-	if (edid) {
+	if (drm_edid) {
 		/* empty probed_modes */
 		INIT_LIST_HEAD(&connector->probed_modes);
 		amdgpu_dm_connector->num_modes =
-				drm_add_edid_modes(connector, edid);
+				drm_edid_connector_add_modes(connector);
 
 		/* sorting the probed modes before calling function
 		 * amdgpu_dm_get_native_mode() since EDID can have
@@ -7345,10 +7345,10 @@ static void amdgpu_dm_connector_ddc_get_modes(struct drm_connector *connector,
 		amdgpu_dm_get_native_mode(connector);
 
 		/* Freesync capabilities are reset by calling
-		 * drm_add_edid_modes() and need to be
+		 * drm_edid_connector_add_modes() and need to be
 		 * restored here.
 		 */
-		amdgpu_dm_update_freesync_caps(connector, edid);
+		amdgpu_dm_update_freesync_caps(connector, drm_edid);
 	} else {
 		amdgpu_dm_connector->num_modes = 0;
 	}
@@ -7444,12 +7444,12 @@ static uint add_fs_modes(struct amdgpu_dm_connector *aconnector)
 }
 
 static void amdgpu_dm_connector_add_freesync_modes(struct drm_connector *connector,
-						   struct edid *edid)
+						   const struct drm_edid *drm_edid)
 {
 	struct amdgpu_dm_connector *amdgpu_dm_connector =
 		to_amdgpu_dm_connector(connector);
 
-	if (!edid)
+	if (!drm_edid)
 		return;
 
 	if (amdgpu_dm_connector->max_vfreq - amdgpu_dm_connector->min_vfreq > 10)
@@ -7462,23 +7462,23 @@ static int amdgpu_dm_connector_get_modes(struct drm_connector *connector)
 	struct amdgpu_dm_connector *amdgpu_dm_connector =
 			to_amdgpu_dm_connector(connector);
 	struct drm_encoder *encoder;
-	struct edid *edid = amdgpu_dm_connector->edid;
+	const struct drm_edid *drm_edid = amdgpu_dm_connector->edid;
 	struct dc_link_settings *verified_link_cap =
 			&amdgpu_dm_connector->dc_link->verified_link_cap;
 	const struct dc *dc = amdgpu_dm_connector->dc_link->dc;
 
 	encoder = amdgpu_dm_connector_to_encoder(connector);
 
-	if (!drm_edid_is_valid(edid)) {
+	if (!drm_edid_valid(drm_edid)) {
 		amdgpu_dm_connector->num_modes =
 				drm_add_modes_noedid(connector, 640, 480);
 		if (dc->link_srv->dp_get_encoding_format(verified_link_cap) == DP_128b_132b_ENCODING)
 			amdgpu_dm_connector->num_modes +=
 				drm_add_modes_noedid(connector, 1920, 1080);
 	} else {
-		amdgpu_dm_connector_ddc_get_modes(connector, edid);
+		amdgpu_dm_connector_ddc_get_modes(connector, drm_edid);
 		amdgpu_dm_connector_add_common_modes(encoder, connector);
-		amdgpu_dm_connector_add_freesync_modes(connector, edid);
+		amdgpu_dm_connector_add_freesync_modes(connector, drm_edid);
 	}
 	amdgpu_dm_fbc_init(connector);
 
@@ -11038,7 +11038,7 @@ static bool parse_edid_cea(struct amdgpu_dm_connector *aconnector,
 }
 
 static int parse_amd_vsdb(struct amdgpu_dm_connector *aconnector,
-			  struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
+			  const struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
 {
 	u8 *edid_ext = NULL;
 	int i;
@@ -11073,7 +11073,8 @@ static int parse_amd_vsdb(struct amdgpu_dm_connector *aconnector,
 }
 
 static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
-		struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
+			       const struct edid *edid,
+			       struct amdgpu_hdmi_vsdb_info *vsdb_info)
 {
 	u8 *edid_ext = NULL;
 	int i;
@@ -11115,7 +11116,7 @@ static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
  * FreeSync parameters.
  */
 void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
-				    struct edid *edid)
+				    const struct drm_edid *drm_edid)
 {
 	int i = 0;
 	struct detailed_timing *timing;
@@ -11125,9 +11126,9 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 			to_amdgpu_dm_connector(connector);
 	struct dm_connector_state *dm_con_state = NULL;
 	struct dc_sink *sink;
-
 	struct amdgpu_device *adev = drm_to_adev(connector->dev);
 	struct amdgpu_hdmi_vsdb_info vsdb_info = {0};
+	const struct edid *edid = drm_edid_raw(drm_edid);
 	bool freesync_capable = false;
 	enum adaptive_sync_type as_type = ADAPTIVE_SYNC_TYPE_NONE;
 
@@ -11140,7 +11141,7 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 		amdgpu_dm_connector->dc_sink :
 		amdgpu_dm_connector->dc_em_sink;
 
-	if (!edid || !sink) {
+	if (!drm_edid || !sink) {
 		dm_con_state = to_dm_connector_state(connector->state);
 
 		amdgpu_dm_connector->min_vfreq = 0;
@@ -11162,7 +11163,7 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 		|| sink->sink_signal == SIGNAL_TYPE_EDP) {
 		bool edid_check_required = false;
 
-		if (edid) {
+		if (drm_edid) {
 			edid_check_required = is_dp_capable_without_timing_msa(
 						adev->dm.dc,
 						amdgpu_dm_connector);
@@ -11214,7 +11215,7 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 			amdgpu_dm_connector->as_type = ADAPTIVE_SYNC_TYPE_EDP;
 		}
 
-	} else if (edid && sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) {
+	} else if (drm_edid && sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) {
 		i = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info);
 		if (i >= 0 && vsdb_info.freesync_supported) {
 			timing  = &edid->detailed_timings[i];
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index 9c1871b866cc..b81cf6f3713b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -637,7 +637,7 @@ struct amdgpu_dm_connector {
 
 	/* we need to mind the EDID between detect
 	   and get modes due to analog/digital/tvencoder */
-	struct edid *edid;
+	const struct drm_edid *edid;
 
 	/* shared with amdgpu */
 	struct amdgpu_hpd hpd;
@@ -908,7 +908,7 @@ void dm_restore_drm_connector_state(struct drm_device *dev,
 				    struct drm_connector *connector);
 
 void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
-					struct edid *edid);
+				    const struct drm_edid *drm_edid);
 
 void amdgpu_dm_trigger_timing_sync(struct drm_device *dev);
 
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index e3915c4f8566..91006326ce6d 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -898,7 +898,8 @@ enum dc_edid_status dm_helpers_read_local_edid(
 	struct i2c_adapter *ddc;
 	int retry = 3;
 	enum dc_edid_status edid_status;
-	struct edid *edid;
+	const struct drm_edid *drm_edid;
+	const struct edid *edid;
 
 	if (link->aux_mode)
 		ddc = &aconnector->dm_dp_aux.aux.ddc;
@@ -909,8 +910,8 @@ enum dc_edid_status dm_helpers_read_local_edid(
 	 * do check sum and retry to make sure read correct edid.
 	 */
 	do {
-
-		edid = drm_get_edid(&aconnector->base, ddc);
+		drm_edid = drm_edid_read_ddc(connector, ddc);
+		edid = drm_edid_raw(drm_edid);
 
 		/* DP Compliance Test 4.2.2.6 */
 		if (link->aux_mode && connector->edid_corrupt)
@@ -928,7 +929,7 @@ enum dc_edid_status dm_helpers_read_local_edid(
 		memmove(sink->dc_edid.raw_edid, (uint8_t *)edid, sink->dc_edid.length);
 
 		/* We don't need the original edid anymore */
-		kfree(edid);
+		drm_edid_free(drm_edid);
 
 		edid_status = dm_helpers_parse_edid_caps(
 						link,
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 7075a85dd16e..cdebd0e74b26 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -127,7 +127,7 @@ dm_dp_mst_connector_destroy(struct drm_connector *connector)
 		dc_sink_release(aconnector->dc_sink);
 	}
 
-	kfree(aconnector->edid);
+	drm_edid_free(aconnector->edid);
 
 	drm_connector_cleanup(connector);
 	drm_dp_mst_put_port_malloc(aconnector->mst_output_port);
@@ -297,15 +297,15 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
 		return drm_add_edid_modes(connector, NULL);
 
 	if (!aconnector->edid) {
-		struct edid *edid;
+		const struct drm_edid *drm_edid;
 
-		edid = drm_dp_mst_get_edid(connector, &aconnector->mst_root->mst_mgr, aconnector->mst_output_port);
+		drm_edid = drm_dp_mst_edid_read(connector, &aconnector->mst_root->mst_mgr, aconnector->mst_output_port);
 
-		if (!edid) {
+		if (!drm_edid) {
 			amdgpu_dm_set_mst_status(&aconnector->mst_status,
 			MST_REMOTE_EDID, false);
 
-			drm_connector_update_edid_property(
+			drm_edid_connector_update(
 				&aconnector->base,
 				NULL);
 
@@ -339,7 +339,7 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
 			return ret;
 		}
 
-		aconnector->edid = edid;
+		aconnector->edid = drm_edid;
 		amdgpu_dm_set_mst_status(&aconnector->mst_status,
 			MST_REMOTE_EDID, true);
 	}
@@ -354,10 +354,12 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
 		struct dc_sink_init_data init_params = {
 				.link = aconnector->dc_link,
 				.sink_signal = SIGNAL_TYPE_DISPLAY_PORT_MST };
+		const struct edid *edid = drm_edid_raw(aconnector->edid);
+
 		dc_sink = dc_link_add_remote_sink(
 			aconnector->dc_link,
-			(uint8_t *)aconnector->edid,
-			(aconnector->edid->extensions + 1) * EDID_LENGTH,
+			(uint8_t *)edid,
+			(edid->extensions + 1) * EDID_LENGTH,
 			&init_params);
 
 		if (!dc_sink) {
@@ -411,10 +413,9 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
 		}
 	}
 
-	drm_connector_update_edid_property(
-					&aconnector->base, aconnector->edid);
+	drm_edid_connector_update(&aconnector->base, aconnector->edid);
 
-	ret = drm_add_edid_modes(connector, aconnector->edid);
+	ret = drm_edid_connector_add_modes(connector);
 
 	return ret;
 }
-- 
2.43.0

Re: [RFC PATCH 0/2] drm/amd/display: switch amdgpu_dm_connector to

[Mario Limonciello]

On 1/26/2024 10:28, Melissa Wen wrote:
> Hi,
> 
> I'm debugging a null-pointer dereference when running
> igt@kms_connector_force_edid and the way I found to solve the bug is to
> stop using raw edid handler in amdgpu_connector_funcs_force and
> create_eml_sink in favor of managing resouces via sruct drm_edid helpers
> (Patch 1). The proper solution seems to be switch amdgpu_dm_connector
> from struct edid to struct drm_edid and avoid the usage of different
> approaches in the driver (Patch 2). However, doing it implies a good
> amount of work and validation, therefore I decided to send this RFC
> first to collect opinions and check if there is any parallel work on
> this side. It's a working in progress.
> 
> The null-pointer error trigger by the igt@kms_connector_force_edid test
> was introduced by:
> - e54ed41620f ("drm/amd/display: Remove unwanted drm edid references")
> 
> You can check the error trace in the first patch.
> 
> This series was tested with kms_hdmi_inject and kms_force_connector. No
> null-pointer error, kms_hdmi_inject is successul and kms_force_connector
> is sucessful after the second execution - the force-edid subtest
> still fails in the first run (I'm still investigating).
> 
> There is also a couple of cast warnings to be addressed - I'm looking
> for the best replacement.
> 
> I appreciate any feedback and testing.

So I'm actually a little bit worried by hardcoding EDID_LENGTH in this 
series.

I have some other patches that I'm posting later on that let you get the 
EDID from _DDC BIOS method too.  My observation was that the EDID can be 
anywhere up to 512 bytes according to the ACPI spec.

An earlier version of my patch was using EDID_LENGTH when fetching it 
and the EDID checksum failed.

I'll CC you on the post, we probably want to get your changes and mine 
merged together.

> 
> Melissa
> 
> Melissa Wen (2):
>    drm/amd/display: fix null-pointer dereference on edid reading
>    drm/amd/display: switch amdgpu_dm_connector to use struct drm_edid
> 
>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 78 ++++++++++---------
>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  4 +-
>   .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  9 ++-
>   .../display/amdgpu_dm/amdgpu_dm_mst_types.c   | 23 +++---
>   4 files changed, 60 insertions(+), 54 deletions(-)
> 

Re: [RFC PATCH 2/2] drm/amd/display: switch amdgpu_dm_connector to use struct drm_edid

[Alex Hung]

On 2024-01-26 09:28, Melissa Wen wrote:
> Replace raw edid handling (struct edid) with the opaque EDID type
> (struct drm_edid) on amdgpu_dm_connector for consistency. It may also
> prevent mismatch of approaches in different parts of the driver code.
> Working in progress. There are a couple of cast warnings and it was only
> tested with IGT.
> 
> Signed-off-by: Melissa Wen <mwen@igalia.com>
> ---
>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 63 ++++++++++---------
>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  4 +-
>   .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  9 +--
>   .../display/amdgpu_dm/amdgpu_dm_mst_types.c   | 23 +++----
>   4 files changed, 51 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 68e71e2ea472..741081d73bb3 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3277,12 +3277,12 @@ void amdgpu_dm_update_connector_after_detect(
>   					&aconnector->dm_dp_aux.aux);
>   			}
>   		} else {
> -			aconnector->edid =
> -				(struct edid *)sink->dc_edid.raw_edid;
> +			const struct edid *edid = (const struct edid *)sink->dc_edid.raw_edid;
> +			aconnector->edid = drm_edid_alloc(edid, (edid->extensions + 1) * EDID_LENGTH);
>   
>   			if (aconnector->dc_link->aux_mode)
>   				drm_dp_cec_set_edid(&aconnector->dm_dp_aux.aux,
> -						    aconnector->edid);
> +						    drm_edid_raw(aconnector->edid));
>   		}
>   
>   		if (!aconnector->timing_requested) {
> @@ -3293,13 +3293,13 @@ void amdgpu_dm_update_connector_after_detect(
>   					"failed to create aconnector->requested_timing\n");
>   		}
>   
> -		drm_connector_update_edid_property(connector, aconnector->edid);
> +		drm_edid_connector_update(connector, aconnector->edid);
>   		amdgpu_dm_update_freesync_caps(connector, aconnector->edid);
>   		update_connector_ext_caps(aconnector);
>   	} else {
>   		drm_dp_cec_unset_edid(&aconnector->dm_dp_aux.aux);
>   		amdgpu_dm_update_freesync_caps(connector, NULL);
> -		drm_connector_update_edid_property(connector, NULL);
> +		drm_edid_connector_update(connector, NULL);
>   		aconnector->num_modes = 0;
>   		dc_sink_release(aconnector->dc_sink);
>   		aconnector->dc_sink = NULL;
> @@ -6564,7 +6564,6 @@ static void amdgpu_dm_connector_funcs_force(struct drm_connector *connector)
>   	struct dc_link *dc_link = aconnector->dc_link;
>   	struct dc_sink *dc_em_sink = aconnector->dc_em_sink;
>   	const struct drm_edid *drm_edid;
> -	const struct edid *edid;
>   
>   	/*
>   	 * Note: drm_get_edid gets edid in the following order:
> @@ -6578,11 +6577,12 @@ static void amdgpu_dm_connector_funcs_force(struct drm_connector *connector)
>   		DRM_ERROR("No EDID found on connector: %s.\n", connector->name);
>   		return;
>   	}
> -	edid = drm_edid_raw(drm_edid);
> -	aconnector->edid = edid;
> -
> +	aconnector->edid = drm_edid;
> +	drm_edid_connector_update(connector, drm_edid);
>   	/* Update emulated (virtual) sink's EDID */
>   	if (dc_em_sink && dc_link) {
> +		const struct edid *edid = drm_edid_raw(drm_edid);
> +
>   		memset(&dc_em_sink->edid_caps, 0, sizeof(struct dc_edid_caps));
>   		memmove(dc_em_sink->dc_edid.raw_edid, (uint8_t *)edid, (edid->extensions + 1) * EDID_LENGTH);
>   		dm_helpers_parse_edid_caps(
> @@ -6633,13 +6633,13 @@ static void create_eml_sink(struct amdgpu_dm_connector *aconnector)
>   		return;
>   	}
>   
> -	edid = drm_edid_raw(drm_edid);
> -
> -	if (drm_detect_hdmi_monitor(edid))
> +	if (connector->display_info.is_hdmi)
>   		init_params.sink_signal = SIGNAL_TYPE_HDMI_TYPE_A;
>   
> -	aconnector->edid = edid;
> +	aconnector->edid = drm_edid;
> +	drm_edid_connector_update(connector, drm_edid);
>   
> +	edid = drm_edid_raw(drm_edid);
>   	aconnector->dc_em_sink = dc_link_add_remote_sink(
>   		aconnector->dc_link,
>   		(uint8_t *)edid,
> @@ -7322,16 +7322,16 @@ static void amdgpu_set_panel_orientation(struct drm_connector *connector)
>   }
>   
>   static void amdgpu_dm_connector_ddc_get_modes(struct drm_connector *connector,
> -					      struct edid *edid)
> +					      const struct drm_edid *drm_edid)
>   {
>   	struct amdgpu_dm_connector *amdgpu_dm_connector =
>   			to_amdgpu_dm_connector(connector);
>   
> -	if (edid) {
> +	if (drm_edid) {
>   		/* empty probed_modes */
>   		INIT_LIST_HEAD(&connector->probed_modes);
>   		amdgpu_dm_connector->num_modes =
> -				drm_add_edid_modes(connector, edid);
> +				drm_edid_connector_add_modes(connector);
>   
>   		/* sorting the probed modes before calling function
>   		 * amdgpu_dm_get_native_mode() since EDID can have
> @@ -7345,10 +7345,10 @@ static void amdgpu_dm_connector_ddc_get_modes(struct drm_connector *connector,
>   		amdgpu_dm_get_native_mode(connector);
>   
>   		/* Freesync capabilities are reset by calling
> -		 * drm_add_edid_modes() and need to be
> +		 * drm_edid_connector_add_modes() and need to be
>   		 * restored here.
>   		 */
> -		amdgpu_dm_update_freesync_caps(connector, edid);
> +		amdgpu_dm_update_freesync_caps(connector, drm_edid);
>   	} else {
>   		amdgpu_dm_connector->num_modes = 0;
>   	}
> @@ -7444,12 +7444,12 @@ static uint add_fs_modes(struct amdgpu_dm_connector *aconnector)
>   }
>   
>   static void amdgpu_dm_connector_add_freesync_modes(struct drm_connector *connector,
> -						   struct edid *edid)
> +						   const struct drm_edid *drm_edid)
>   {
>   	struct amdgpu_dm_connector *amdgpu_dm_connector =
>   		to_amdgpu_dm_connector(connector);
>   
> -	if (!edid)
> +	if (!drm_edid)
>   		return;
>   
>   	if (amdgpu_dm_connector->max_vfreq - amdgpu_dm_connector->min_vfreq > 10)
> @@ -7462,23 +7462,23 @@ static int amdgpu_dm_connector_get_modes(struct drm_connector *connector)
>   	struct amdgpu_dm_connector *amdgpu_dm_connector =
>   			to_amdgpu_dm_connector(connector);
>   	struct drm_encoder *encoder;
> -	struct edid *edid = amdgpu_dm_connector->edid;
> +	const struct drm_edid *drm_edid = amdgpu_dm_connector->edid;
>   	struct dc_link_settings *verified_link_cap =
>   			&amdgpu_dm_connector->dc_link->verified_link_cap;
>   	const struct dc *dc = amdgpu_dm_connector->dc_link->dc;
>   
>   	encoder = amdgpu_dm_connector_to_encoder(connector);
>   
> -	if (!drm_edid_is_valid(edid)) {
> +	if (!drm_edid_valid(drm_edid)) {
>   		amdgpu_dm_connector->num_modes =
>   				drm_add_modes_noedid(connector, 640, 480);
>   		if (dc->link_srv->dp_get_encoding_format(verified_link_cap) == DP_128b_132b_ENCODING)
>   			amdgpu_dm_connector->num_modes +=
>   				drm_add_modes_noedid(connector, 1920, 1080);
>   	} else {
> -		amdgpu_dm_connector_ddc_get_modes(connector, edid);
> +		amdgpu_dm_connector_ddc_get_modes(connector, drm_edid);
>   		amdgpu_dm_connector_add_common_modes(encoder, connector);
> -		amdgpu_dm_connector_add_freesync_modes(connector, edid);
> +		amdgpu_dm_connector_add_freesync_modes(connector, drm_edid);
>   	}
>   	amdgpu_dm_fbc_init(connector);
>   
> @@ -11038,7 +11038,7 @@ static bool parse_edid_cea(struct amdgpu_dm_connector *aconnector,
>   }
>   
>   static int parse_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> -			  struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
> +			  const struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
>   {
>   	u8 *edid_ext = NULL;
>   	int i;
> @@ -11073,7 +11073,8 @@ static int parse_amd_vsdb(struct amdgpu_dm_connector *aconnector,
>   }
>   
>   static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> -		struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
> +			       const struct edid *edid,
> +			       struct amdgpu_hdmi_vsdb_info *vsdb_info)
>   {
>   	u8 *edid_ext = NULL;
>   	int i;
> @@ -11115,7 +11116,7 @@ static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
>    * FreeSync parameters.
>    */
>   void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> -				    struct edid *edid)
> +				    const struct drm_edid *drm_edid)
>   {
>   	int i = 0;
>   	struct detailed_timing *timing;
> @@ -11125,9 +11126,9 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
>   			to_amdgpu_dm_connector(connector);
>   	struct dm_connector_state *dm_con_state = NULL;
>   	struct dc_sink *sink;
> -
>   	struct amdgpu_device *adev = drm_to_adev(connector->dev);
>   	struct amdgpu_hdmi_vsdb_info vsdb_info = {0};
> +	const struct edid *edid = drm_edid_raw(drm_edid);


I got below compile errors:

drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c: In function 
‘amdgpu_dm_update_freesync_caps’:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:11176:41: 
error: assignment discards ‘const’ qualifier from pointer target type 
[-Werror=discarded-qualifiers]
11176 |                                 timing  = 
&edid->detailed_timings[i];
       |                                         ^
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:11221:33: 
error: assignment discards ‘const’ qualifier from pointer target type 
[-Werror=discarded-qualifiers]
11221 |                         timing  = &edid->detailed_timings[i];


and the following changes fixes it:

-       struct detailed_timing *timing;
-       struct detailed_non_pixel *data;
-       struct detailed_data_monitor_range *range;
+       const struct detailed_timing *timing;
+       const struct detailed_non_pixel *data;
+       const struct detailed_data_monitor_range *range;




>   	bool freesync_capable = false;
>   	enum adaptive_sync_type as_type = ADAPTIVE_SYNC_TYPE_NONE;
>   
> @@ -11140,7 +11141,7 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
>   		amdgpu_dm_connector->dc_sink :
>   		amdgpu_dm_connector->dc_em_sink;
>   
> -	if (!edid || !sink) {
> +	if (!drm_edid || !sink) {
>   		dm_con_state = to_dm_connector_state(connector->state);
>   
>   		amdgpu_dm_connector->min_vfreq = 0;
> @@ -11162,7 +11163,7 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
>   		|| sink->sink_signal == SIGNAL_TYPE_EDP) {
>   		bool edid_check_required = false;
>   
> -		if (edid) {
> +		if (drm_edid) {
>   			edid_check_required = is_dp_capable_without_timing_msa(
>   						adev->dm.dc,
>   						amdgpu_dm_connector);
> @@ -11214,7 +11215,7 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
>   			amdgpu_dm_connector->as_type = ADAPTIVE_SYNC_TYPE_EDP;
>   		}
>   
> -	} else if (edid && sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) {
> +	} else if (drm_edid && sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) {
>   		i = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info);
>   		if (i >= 0 && vsdb_info.freesync_supported) {
>   			timing  = &edid->detailed_timings[i];
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> index 9c1871b866cc..b81cf6f3713b 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> @@ -637,7 +637,7 @@ struct amdgpu_dm_connector {
>   
>   	/* we need to mind the EDID between detect
>   	   and get modes due to analog/digital/tvencoder */
> -	struct edid *edid;
> +	const struct drm_edid *edid;
>   
>   	/* shared with amdgpu */
>   	struct amdgpu_hpd hpd;
> @@ -908,7 +908,7 @@ void dm_restore_drm_connector_state(struct drm_device *dev,
>   				    struct drm_connector *connector);
>   
>   void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> -					struct edid *edid);
> +				    const struct drm_edid *drm_edid);
>   
>   void amdgpu_dm_trigger_timing_sync(struct drm_device *dev);
>   
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> index e3915c4f8566..91006326ce6d 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> @@ -898,7 +898,8 @@ enum dc_edid_status dm_helpers_read_local_edid(
>   	struct i2c_adapter *ddc;
>   	int retry = 3;
>   	enum dc_edid_status edid_status;
> -	struct edid *edid;
> +	const struct drm_edid *drm_edid;
> +	const struct edid *edid;
>   
>   	if (link->aux_mode)
>   		ddc = &aconnector->dm_dp_aux.aux.ddc;
> @@ -909,8 +910,8 @@ enum dc_edid_status dm_helpers_read_local_edid(
>   	 * do check sum and retry to make sure read correct edid.
>   	 */
>   	do {
> -
> -		edid = drm_get_edid(&aconnector->base, ddc);
> +		drm_edid = drm_edid_read_ddc(connector, ddc);
> +		edid = drm_edid_raw(drm_edid);
>   
>   		/* DP Compliance Test 4.2.2.6 */
>   		if (link->aux_mode && connector->edid_corrupt)
> @@ -928,7 +929,7 @@ enum dc_edid_status dm_helpers_read_local_edid(
>   		memmove(sink->dc_edid.raw_edid, (uint8_t *)edid, sink->dc_edid.length);
>   
>   		/* We don't need the original edid anymore */
> -		kfree(edid);
> +		drm_edid_free(drm_edid);
>   
>   		edid_status = dm_helpers_parse_edid_caps(
>   						link,
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> index 7075a85dd16e..cdebd0e74b26 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> @@ -127,7 +127,7 @@ dm_dp_mst_connector_destroy(struct drm_connector *connector)
>   		dc_sink_release(aconnector->dc_sink);
>   	}
>   
> -	kfree(aconnector->edid);
> +	drm_edid_free(aconnector->edid);
>   
>   	drm_connector_cleanup(connector);
>   	drm_dp_mst_put_port_malloc(aconnector->mst_output_port);
> @@ -297,15 +297,15 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
>   		return drm_add_edid_modes(connector, NULL);
>   
>   	if (!aconnector->edid) {
> -		struct edid *edid;
> +		const struct drm_edid *drm_edid;
>   
> -		edid = drm_dp_mst_get_edid(connector, &aconnector->mst_root->mst_mgr, aconnector->mst_output_port);
> +		drm_edid = drm_dp_mst_edid_read(connector, &aconnector->mst_root->mst_mgr, aconnector->mst_output_port);
>   
> -		if (!edid) {
> +		if (!drm_edid) {
>   			amdgpu_dm_set_mst_status(&aconnector->mst_status,
>   			MST_REMOTE_EDID, false);
>   
> -			drm_connector_update_edid_property(
> +			drm_edid_connector_update(
>   				&aconnector->base,
>   				NULL);
>   
> @@ -339,7 +339,7 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
>   			return ret;
>   		}
>   
> -		aconnector->edid = edid;
> +		aconnector->edid = drm_edid;
>   		amdgpu_dm_set_mst_status(&aconnector->mst_status,
>   			MST_REMOTE_EDID, true);
>   	}
> @@ -354,10 +354,12 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
>   		struct dc_sink_init_data init_params = {
>   				.link = aconnector->dc_link,
>   				.sink_signal = SIGNAL_TYPE_DISPLAY_PORT_MST };
> +		const struct edid *edid = drm_edid_raw(aconnector->edid);
> +
>   		dc_sink = dc_link_add_remote_sink(
>   			aconnector->dc_link,
> -			(uint8_t *)aconnector->edid,
> -			(aconnector->edid->extensions + 1) * EDID_LENGTH,
> +			(uint8_t *)edid,
> +			(edid->extensions + 1) * EDID_LENGTH,
>   			&init_params);
>   
>   		if (!dc_sink) {
> @@ -411,10 +413,9 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
>   		}
>   	}
>   
> -	drm_connector_update_edid_property(
> -					&aconnector->base, aconnector->edid);
> +	drm_edid_connector_update(&aconnector->base, aconnector->edid);
>   
> -	ret = drm_add_edid_modes(connector, aconnector->edid);
> +	ret = drm_edid_connector_add_modes(connector);
>   
>   	return ret;
>   }

Re: [RFC PATCH 0/2] drm/amd/display: switch amdgpu_dm_connector to

[Jani Nikula]

On Fri, 26 Jan 2024, Mario Limonciello <mario.limonciello@amd.com> wrote:
> On 1/26/2024 10:28, Melissa Wen wrote:
>> Hi,
>> 
>> I'm debugging a null-pointer dereference when running
>> igt@kms_connector_force_edid and the way I found to solve the bug is to
>> stop using raw edid handler in amdgpu_connector_funcs_force and
>> create_eml_sink in favor of managing resouces via sruct drm_edid helpers
>> (Patch 1). The proper solution seems to be switch amdgpu_dm_connector
>> from struct edid to struct drm_edid and avoid the usage of different
>> approaches in the driver (Patch 2). However, doing it implies a good
>> amount of work and validation, therefore I decided to send this RFC
>> first to collect opinions and check if there is any parallel work on
>> this side. It's a working in progress.
>> 
>> The null-pointer error trigger by the igt@kms_connector_force_edid test
>> was introduced by:
>> - e54ed41620f ("drm/amd/display: Remove unwanted drm edid references")
>> 
>> You can check the error trace in the first patch.
>> 
>> This series was tested with kms_hdmi_inject and kms_force_connector. No
>> null-pointer error, kms_hdmi_inject is successul and kms_force_connector
>> is sucessful after the second execution - the force-edid subtest
>> still fails in the first run (I'm still investigating).
>> 
>> There is also a couple of cast warnings to be addressed - I'm looking
>> for the best replacement.
>> 
>> I appreciate any feedback and testing.
>
> So I'm actually a little bit worried by hardcoding EDID_LENGTH in this 
> series.
>
> I have some other patches that I'm posting later on that let you get the 
> EDID from _DDC BIOS method too.  My observation was that the EDID can be 
> anywhere up to 512 bytes according to the ACPI spec.
>
> An earlier version of my patch was using EDID_LENGTH when fetching it 
> and the EDID checksum failed.
>
> I'll CC you on the post, we probably want to get your changes and mine 
> merged together.

One of the main points of struct drm_edid is that it tracks the
allocation size separately.

We should simply not trust edid->extensions, because most of the time it
originates from outside the kernel.

Using drm_edid and immediately drm_edid_raw() falls short. That function
should only be used during migration to help. And yeah, it also means
EDID parsing should be done in drm_edid.c, and not spread out all over
the subsystem.


BR,
Jani.


>
>> 
>> Melissa
>> 
>> Melissa Wen (2):
>>    drm/amd/display: fix null-pointer dereference on edid reading
>>    drm/amd/display: switch amdgpu_dm_connector to use struct drm_edid
>> 
>>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 78 ++++++++++---------
>>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  4 +-
>>   .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  9 ++-
>>   .../display/amdgpu_dm/amdgpu_dm_mst_types.c   | 23 +++---
>>   4 files changed, 60 insertions(+), 54 deletions(-)
>> 
>

-- 
Jani Nikula, Intel

Re: [RFC PATCH 0/2] drm/amd/display: switch amdgpu_dm_connector to

[Melissa Wen]

On 01/29, Jani Nikula wrote:
> On Fri, 26 Jan 2024, Mario Limonciello <mario.limonciello@amd.com> wrote:
> > On 1/26/2024 10:28, Melissa Wen wrote:
> >> Hi,
> >> 
> >> I'm debugging a null-pointer dereference when running
> >> igt@kms_connector_force_edid and the way I found to solve the bug is to
> >> stop using raw edid handler in amdgpu_connector_funcs_force and
> >> create_eml_sink in favor of managing resouces via sruct drm_edid helpers
> >> (Patch 1). The proper solution seems to be switch amdgpu_dm_connector
> >> from struct edid to struct drm_edid and avoid the usage of different
> >> approaches in the driver (Patch 2). However, doing it implies a good
> >> amount of work and validation, therefore I decided to send this RFC
> >> first to collect opinions and check if there is any parallel work on
> >> this side. It's a working in progress.
> >> 
> >> The null-pointer error trigger by the igt@kms_connector_force_edid test
> >> was introduced by:
> >> - e54ed41620f ("drm/amd/display: Remove unwanted drm edid references")
> >> 
> >> You can check the error trace in the first patch.
> >> 
> >> This series was tested with kms_hdmi_inject and kms_force_connector. No
> >> null-pointer error, kms_hdmi_inject is successul and kms_force_connector
> >> is sucessful after the second execution - the force-edid subtest
> >> still fails in the first run (I'm still investigating).
> >> 
> >> There is also a couple of cast warnings to be addressed - I'm looking
> >> for the best replacement.
> >> 
> >> I appreciate any feedback and testing.
> >
> > So I'm actually a little bit worried by hardcoding EDID_LENGTH in this 
> > series.
> >
> > I have some other patches that I'm posting later on that let you get the 
> > EDID from _DDC BIOS method too.  My observation was that the EDID can be 
> > anywhere up to 512 bytes according to the ACPI spec.
> >
> > An earlier version of my patch was using EDID_LENGTH when fetching it 
> > and the EDID checksum failed.
> >
> > I'll CC you on the post, we probably want to get your changes and mine 
> > merged together.
> 
> One of the main points of struct drm_edid is that it tracks the
> allocation size separately.
> 
> We should simply not trust edid->extensions, because most of the time it
> originates from outside the kernel.
> 
> Using drm_edid and immediately drm_edid_raw() falls short. That function
> should only be used during migration to help. And yeah, it also means
> EDID parsing should be done in drm_edid.c, and not spread out all over
> the subsystem.

Hi Mario and Jani,

Thanks for the feedback.

I agree with you. I used the drm_edid_raw() as an intermediate step to
assess/validate this migration, but I'll work on removing this hack.

So, I understand that the transition from edid to drm_edid is the right
path, so I'll improve this work (keeping the points you raised in mind)
and send a version.

BR,

Melissa
> 
> 
> BR,
> Jani.
> 
> 
> >
> >> 
> >> Melissa
> >> 
> >> Melissa Wen (2):
> >>    drm/amd/display: fix null-pointer dereference on edid reading
> >>    drm/amd/display: switch amdgpu_dm_connector to use struct drm_edid
> >> 
> >>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 78 ++++++++++---------
> >>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  4 +-
> >>   .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  9 ++-
> >>   .../display/amdgpu_dm/amdgpu_dm_mst_types.c   | 23 +++---
> >>   4 files changed, 60 insertions(+), 54 deletions(-)
> >> 
> >
> 
> -- 
> Jani Nikula, Intel

Re: [RFC PATCH 2/2] drm/amd/display: switch amdgpu_dm_connector to use struct drm_edid

[Melissa Wen]

On 01/26, Alex Hung wrote:
> 
> 
> On 2024-01-26 09:28, Melissa Wen wrote:
> > Replace raw edid handling (struct edid) with the opaque EDID type
> > (struct drm_edid) on amdgpu_dm_connector for consistency. It may also
> > prevent mismatch of approaches in different parts of the driver code.
> > Working in progress. There are a couple of cast warnings and it was only
> > tested with IGT.
> > 
> > Signed-off-by: Melissa Wen <mwen@igalia.com>
> > ---
> >   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 63 ++++++++++---------
> >   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  4 +-
> >   .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  9 +--
> >   .../display/amdgpu_dm/amdgpu_dm_mst_types.c   | 23 +++----
> >   4 files changed, 51 insertions(+), 48 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index 68e71e2ea472..741081d73bb3 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -3277,12 +3277,12 @@ void amdgpu_dm_update_connector_after_detect(
> >   					&aconnector->dm_dp_aux.aux);
> >   			}
> >   		} else {
> > -			aconnector->edid =
> > -				(struct edid *)sink->dc_edid.raw_edid;
> > +			const struct edid *edid = (const struct edid *)sink->dc_edid.raw_edid;
> > +			aconnector->edid = drm_edid_alloc(edid, (edid->extensions + 1) * EDID_LENGTH);
> >   			if (aconnector->dc_link->aux_mode)
> >   				drm_dp_cec_set_edid(&aconnector->dm_dp_aux.aux,
> > -						    aconnector->edid);
> > +						    drm_edid_raw(aconnector->edid));
> >   		}
> >   		if (!aconnector->timing_requested) {
> > @@ -3293,13 +3293,13 @@ void amdgpu_dm_update_connector_after_detect(
> >   					"failed to create aconnector->requested_timing\n");
> >   		}
> > -		drm_connector_update_edid_property(connector, aconnector->edid);
> > +		drm_edid_connector_update(connector, aconnector->edid);
> >   		amdgpu_dm_update_freesync_caps(connector, aconnector->edid);
> >   		update_connector_ext_caps(aconnector);
> >   	} else {
> >   		drm_dp_cec_unset_edid(&aconnector->dm_dp_aux.aux);
> >   		amdgpu_dm_update_freesync_caps(connector, NULL);
> > -		drm_connector_update_edid_property(connector, NULL);
> > +		drm_edid_connector_update(connector, NULL);
> >   		aconnector->num_modes = 0;
> >   		dc_sink_release(aconnector->dc_sink);
> >   		aconnector->dc_sink = NULL;
> > @@ -6564,7 +6564,6 @@ static void amdgpu_dm_connector_funcs_force(struct drm_connector *connector)
> >   	struct dc_link *dc_link = aconnector->dc_link;
> >   	struct dc_sink *dc_em_sink = aconnector->dc_em_sink;
> >   	const struct drm_edid *drm_edid;
> > -	const struct edid *edid;
> >   	/*
> >   	 * Note: drm_get_edid gets edid in the following order:
> > @@ -6578,11 +6577,12 @@ static void amdgpu_dm_connector_funcs_force(struct drm_connector *connector)
> >   		DRM_ERROR("No EDID found on connector: %s.\n", connector->name);
> >   		return;
> >   	}
> > -	edid = drm_edid_raw(drm_edid);
> > -	aconnector->edid = edid;
> > -
> > +	aconnector->edid = drm_edid;
> > +	drm_edid_connector_update(connector, drm_edid);
> >   	/* Update emulated (virtual) sink's EDID */
> >   	if (dc_em_sink && dc_link) {
> > +		const struct edid *edid = drm_edid_raw(drm_edid);
> > +
> >   		memset(&dc_em_sink->edid_caps, 0, sizeof(struct dc_edid_caps));
> >   		memmove(dc_em_sink->dc_edid.raw_edid, (uint8_t *)edid, (edid->extensions + 1) * EDID_LENGTH);
> >   		dm_helpers_parse_edid_caps(
> > @@ -6633,13 +6633,13 @@ static void create_eml_sink(struct amdgpu_dm_connector *aconnector)
> >   		return;
> >   	}
> > -	edid = drm_edid_raw(drm_edid);
> > -
> > -	if (drm_detect_hdmi_monitor(edid))
> > +	if (connector->display_info.is_hdmi)
> >   		init_params.sink_signal = SIGNAL_TYPE_HDMI_TYPE_A;
> > -	aconnector->edid = edid;
> > +	aconnector->edid = drm_edid;
> > +	drm_edid_connector_update(connector, drm_edid);
> > +	edid = drm_edid_raw(drm_edid);
> >   	aconnector->dc_em_sink = dc_link_add_remote_sink(
> >   		aconnector->dc_link,
> >   		(uint8_t *)edid,
> > @@ -7322,16 +7322,16 @@ static void amdgpu_set_panel_orientation(struct drm_connector *connector)
> >   }
> >   static void amdgpu_dm_connector_ddc_get_modes(struct drm_connector *connector,
> > -					      struct edid *edid)
> > +					      const struct drm_edid *drm_edid)
> >   {
> >   	struct amdgpu_dm_connector *amdgpu_dm_connector =
> >   			to_amdgpu_dm_connector(connector);
> > -	if (edid) {
> > +	if (drm_edid) {
> >   		/* empty probed_modes */
> >   		INIT_LIST_HEAD(&connector->probed_modes);
> >   		amdgpu_dm_connector->num_modes =
> > -				drm_add_edid_modes(connector, edid);
> > +				drm_edid_connector_add_modes(connector);
> >   		/* sorting the probed modes before calling function
> >   		 * amdgpu_dm_get_native_mode() since EDID can have
> > @@ -7345,10 +7345,10 @@ static void amdgpu_dm_connector_ddc_get_modes(struct drm_connector *connector,
> >   		amdgpu_dm_get_native_mode(connector);
> >   		/* Freesync capabilities are reset by calling
> > -		 * drm_add_edid_modes() and need to be
> > +		 * drm_edid_connector_add_modes() and need to be
> >   		 * restored here.
> >   		 */
> > -		amdgpu_dm_update_freesync_caps(connector, edid);
> > +		amdgpu_dm_update_freesync_caps(connector, drm_edid);
> >   	} else {
> >   		amdgpu_dm_connector->num_modes = 0;
> >   	}
> > @@ -7444,12 +7444,12 @@ static uint add_fs_modes(struct amdgpu_dm_connector *aconnector)
> >   }
> >   static void amdgpu_dm_connector_add_freesync_modes(struct drm_connector *connector,
> > -						   struct edid *edid)
> > +						   const struct drm_edid *drm_edid)
> >   {
> >   	struct amdgpu_dm_connector *amdgpu_dm_connector =
> >   		to_amdgpu_dm_connector(connector);
> > -	if (!edid)
> > +	if (!drm_edid)
> >   		return;
> >   	if (amdgpu_dm_connector->max_vfreq - amdgpu_dm_connector->min_vfreq > 10)
> > @@ -7462,23 +7462,23 @@ static int amdgpu_dm_connector_get_modes(struct drm_connector *connector)
> >   	struct amdgpu_dm_connector *amdgpu_dm_connector =
> >   			to_amdgpu_dm_connector(connector);
> >   	struct drm_encoder *encoder;
> > -	struct edid *edid = amdgpu_dm_connector->edid;
> > +	const struct drm_edid *drm_edid = amdgpu_dm_connector->edid;
> >   	struct dc_link_settings *verified_link_cap =
> >   			&amdgpu_dm_connector->dc_link->verified_link_cap;
> >   	const struct dc *dc = amdgpu_dm_connector->dc_link->dc;
> >   	encoder = amdgpu_dm_connector_to_encoder(connector);
> > -	if (!drm_edid_is_valid(edid)) {
> > +	if (!drm_edid_valid(drm_edid)) {
> >   		amdgpu_dm_connector->num_modes =
> >   				drm_add_modes_noedid(connector, 640, 480);
> >   		if (dc->link_srv->dp_get_encoding_format(verified_link_cap) == DP_128b_132b_ENCODING)
> >   			amdgpu_dm_connector->num_modes +=
> >   				drm_add_modes_noedid(connector, 1920, 1080);
> >   	} else {
> > -		amdgpu_dm_connector_ddc_get_modes(connector, edid);
> > +		amdgpu_dm_connector_ddc_get_modes(connector, drm_edid);
> >   		amdgpu_dm_connector_add_common_modes(encoder, connector);
> > -		amdgpu_dm_connector_add_freesync_modes(connector, edid);
> > +		amdgpu_dm_connector_add_freesync_modes(connector, drm_edid);
> >   	}
> >   	amdgpu_dm_fbc_init(connector);
> > @@ -11038,7 +11038,7 @@ static bool parse_edid_cea(struct amdgpu_dm_connector *aconnector,
> >   }
> >   static int parse_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> > -			  struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
> > +			  const struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
> >   {
> >   	u8 *edid_ext = NULL;
> >   	int i;
> > @@ -11073,7 +11073,8 @@ static int parse_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> >   }
> >   static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> > -		struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
> > +			       const struct edid *edid,
> > +			       struct amdgpu_hdmi_vsdb_info *vsdb_info)
> >   {
> >   	u8 *edid_ext = NULL;
> >   	int i;
> > @@ -11115,7 +11116,7 @@ static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> >    * FreeSync parameters.
> >    */
> >   void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> > -				    struct edid *edid)
> > +				    const struct drm_edid *drm_edid)
> >   {
> >   	int i = 0;
> >   	struct detailed_timing *timing;
> > @@ -11125,9 +11126,9 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> >   			to_amdgpu_dm_connector(connector);
> >   	struct dm_connector_state *dm_con_state = NULL;
> >   	struct dc_sink *sink;
> > -
> >   	struct amdgpu_device *adev = drm_to_adev(connector->dev);
> >   	struct amdgpu_hdmi_vsdb_info vsdb_info = {0};
> > +	const struct edid *edid = drm_edid_raw(drm_edid);
> 
> 
> I got below compile errors:
> 
> drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c: In function
> ‘amdgpu_dm_update_freesync_caps’:
> drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:11176:41: error:
> assignment discards ‘const’ qualifier from pointer target type
> [-Werror=discarded-qualifiers]
> 11176 |                                 timing  =
> &edid->detailed_timings[i];
>       |                                         ^
> drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:11221:33: error:
> assignment discards ‘const’ qualifier from pointer target type
> [-Werror=discarded-qualifiers]
> 11221 |                         timing  = &edid->detailed_timings[i];
> 
> 
> and the following changes fixes it:
> 
> -       struct detailed_timing *timing;
> -       struct detailed_non_pixel *data;
> -       struct detailed_data_monitor_range *range;
> +       const struct detailed_timing *timing;
> +       const struct detailed_non_pixel *data;
> +       const struct detailed_data_monitor_range *range;

Oh, thanks! I didn't realize this fast path to fix these warnings.

I'm considering to replace it with a drm_edid helper in the next version
and avoid handling `struct edid` in the driver.

I'll work on it for the next version.

BR,

Melissa

> 
> 
> 
> 
> >   	bool freesync_capable = false;
> >   	enum adaptive_sync_type as_type = ADAPTIVE_SYNC_TYPE_NONE;
> > @@ -11140,7 +11141,7 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> >   		amdgpu_dm_connector->dc_sink :
> >   		amdgpu_dm_connector->dc_em_sink;
> > -	if (!edid || !sink) {
> > +	if (!drm_edid || !sink) {
> >   		dm_con_state = to_dm_connector_state(connector->state);
> >   		amdgpu_dm_connector->min_vfreq = 0;
> > @@ -11162,7 +11163,7 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> >   		|| sink->sink_signal == SIGNAL_TYPE_EDP) {
> >   		bool edid_check_required = false;
> > -		if (edid) {
> > +		if (drm_edid) {
> >   			edid_check_required = is_dp_capable_without_timing_msa(
> >   						adev->dm.dc,
> >   						amdgpu_dm_connector);
> > @@ -11214,7 +11215,7 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> >   			amdgpu_dm_connector->as_type = ADAPTIVE_SYNC_TYPE_EDP;
> >   		}
> > -	} else if (edid && sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) {
> > +	} else if (drm_edid && sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) {
> >   		i = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info);
> >   		if (i >= 0 && vsdb_info.freesync_supported) {
> >   			timing  = &edid->detailed_timings[i];
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> > index 9c1871b866cc..b81cf6f3713b 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> > @@ -637,7 +637,7 @@ struct amdgpu_dm_connector {
> >   	/* we need to mind the EDID between detect
> >   	   and get modes due to analog/digital/tvencoder */
> > -	struct edid *edid;
> > +	const struct drm_edid *edid;
> >   	/* shared with amdgpu */
> >   	struct amdgpu_hpd hpd;
> > @@ -908,7 +908,7 @@ void dm_restore_drm_connector_state(struct drm_device *dev,
> >   				    struct drm_connector *connector);
> >   void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> > -					struct edid *edid);
> > +				    const struct drm_edid *drm_edid);
> >   void amdgpu_dm_trigger_timing_sync(struct drm_device *dev);
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > index e3915c4f8566..91006326ce6d 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > @@ -898,7 +898,8 @@ enum dc_edid_status dm_helpers_read_local_edid(
> >   	struct i2c_adapter *ddc;
> >   	int retry = 3;
> >   	enum dc_edid_status edid_status;
> > -	struct edid *edid;
> > +	const struct drm_edid *drm_edid;
> > +	const struct edid *edid;
> >   	if (link->aux_mode)
> >   		ddc = &aconnector->dm_dp_aux.aux.ddc;
> > @@ -909,8 +910,8 @@ enum dc_edid_status dm_helpers_read_local_edid(
> >   	 * do check sum and retry to make sure read correct edid.
> >   	 */
> >   	do {
> > -
> > -		edid = drm_get_edid(&aconnector->base, ddc);
> > +		drm_edid = drm_edid_read_ddc(connector, ddc);
> > +		edid = drm_edid_raw(drm_edid);
> >   		/* DP Compliance Test 4.2.2.6 */
> >   		if (link->aux_mode && connector->edid_corrupt)
> > @@ -928,7 +929,7 @@ enum dc_edid_status dm_helpers_read_local_edid(
> >   		memmove(sink->dc_edid.raw_edid, (uint8_t *)edid, sink->dc_edid.length);
> >   		/* We don't need the original edid anymore */
> > -		kfree(edid);
> > +		drm_edid_free(drm_edid);
> >   		edid_status = dm_helpers_parse_edid_caps(
> >   						link,
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > index 7075a85dd16e..cdebd0e74b26 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > @@ -127,7 +127,7 @@ dm_dp_mst_connector_destroy(struct drm_connector *connector)
> >   		dc_sink_release(aconnector->dc_sink);
> >   	}
> > -	kfree(aconnector->edid);
> > +	drm_edid_free(aconnector->edid);
> >   	drm_connector_cleanup(connector);
> >   	drm_dp_mst_put_port_malloc(aconnector->mst_output_port);
> > @@ -297,15 +297,15 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
> >   		return drm_add_edid_modes(connector, NULL);
> >   	if (!aconnector->edid) {
> > -		struct edid *edid;
> > +		const struct drm_edid *drm_edid;
> > -		edid = drm_dp_mst_get_edid(connector, &aconnector->mst_root->mst_mgr, aconnector->mst_output_port);
> > +		drm_edid = drm_dp_mst_edid_read(connector, &aconnector->mst_root->mst_mgr, aconnector->mst_output_port);
> > -		if (!edid) {
> > +		if (!drm_edid) {
> >   			amdgpu_dm_set_mst_status(&aconnector->mst_status,
> >   			MST_REMOTE_EDID, false);
> > -			drm_connector_update_edid_property(
> > +			drm_edid_connector_update(
> >   				&aconnector->base,
> >   				NULL);
> > @@ -339,7 +339,7 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
> >   			return ret;
> >   		}
> > -		aconnector->edid = edid;
> > +		aconnector->edid = drm_edid;
> >   		amdgpu_dm_set_mst_status(&aconnector->mst_status,
> >   			MST_REMOTE_EDID, true);
> >   	}
> > @@ -354,10 +354,12 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
> >   		struct dc_sink_init_data init_params = {
> >   				.link = aconnector->dc_link,
> >   				.sink_signal = SIGNAL_TYPE_DISPLAY_PORT_MST };
> > +		const struct edid *edid = drm_edid_raw(aconnector->edid);
> > +
> >   		dc_sink = dc_link_add_remote_sink(
> >   			aconnector->dc_link,
> > -			(uint8_t *)aconnector->edid,
> > -			(aconnector->edid->extensions + 1) * EDID_LENGTH,
> > +			(uint8_t *)edid,
> > +			(edid->extensions + 1) * EDID_LENGTH,
> >   			&init_params);
> >   		if (!dc_sink) {
> > @@ -411,10 +413,9 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
> >   		}
> >   	}
> > -	drm_connector_update_edid_property(
> > -					&aconnector->base, aconnector->edid);
> > +	drm_edid_connector_update(&aconnector->base, aconnector->edid);
> > -	ret = drm_add_edid_modes(connector, aconnector->edid);
> > +	ret = drm_edid_connector_add_modes(connector);
> >   	return ret;
> >   }