From: Alex Hung <alex.hung@amd.com>
To: "Timur Kristóf" <timur.kristof@gmail.com>,
amd-gfx@lists.freedesktop.org, Alexander.Deucher@amd.com,
Christian.Koenig@amd.com,
"Mario Limonciello" <mario.limonciello@amd.com>,
"Ivan Lipski" <ivan.lipski@amd.com>,
"Prike Liang" <Prike.Liang@amd.com>,
"Leo Li" <sunpeng.li@amd.com>, "Ray Wu" <Ray.Wu@amd.com>,
siqueira@igalia.com
Subject: Re: [PATCH 05/14] drm/amd/display: Refactor DAC load detection, move to HWSS
Date: Fri, 30 Jan 2026 13:00:52 -0700 [thread overview]
Message-ID: <e1d478b2-99a4-40af-94c9-5eddc72a717b@amd.com> (raw)
In-Reply-To: <20260126210837.21885-6-timur.kristof@gmail.com>
On 1/26/26 14:08, Timur Kristóf wrote:
> Slightly refactor and simplify DAC load detection.
> This prepares the code to be used for also executing DAC
> load detection on external DP bridge encoders.
>
> DAC load detection belongs better in the hardware sequencer
> code because the implementation is HW dependent and not all
> chips support the functionality. The code is cleaner when
> link detection probably doesn't call the VBIOS directly.
>
> Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
> ---
> .../gpu/drm/amd/display/dc/bios/bios_parser.c | 25 ++++++++-----------
> .../gpu/drm/amd/display/dc/dc_bios_types.h | 4 +--
> .../amd/display/dc/hwss/dce110/dce110_hwseq.c | 12 +++++++++
> .../drm/amd/display/dc/hwss/hw_sequencer.h | 1 +
> .../drm/amd/display/dc/link/link_detection.c | 24 +++---------------
> 5 files changed, 28 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
> index 9f11e6ca4051..e2b74dda00fc 100644
> --- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
> +++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
> @@ -782,26 +782,17 @@ static enum bp_result bios_parser_encoder_control(
>
> static enum bp_result bios_parser_dac_load_detection(
> struct dc_bios *dcb,
> - enum engine_id engine_id,
> - enum dal_device_type device_type,
> - uint32_t enum_id)
> + enum engine_id engine_id)
> {
> struct bios_parser *bp = BP_FROM_DCB(dcb);
> struct dc_context *ctx = dcb->ctx;
> struct bp_load_detection_parameters bp_params = {0};
> - enum bp_result bp_result;
> + enum bp_result bp_result = BP_RESULT_UNSUPPORTED;
> uint32_t bios_0_scratch;
> uint32_t device_id_mask = 0;
>
> - bp_params.engine_id = engine_id;
> - bp_params.device_id = get_support_mask_for_device_id(device_type, enum_id);
> -
> - if (engine_id != ENGINE_ID_DACA &&
> - engine_id != ENGINE_ID_DACB)
> - return BP_RESULT_UNSUPPORTED;
> -
> - if (!bp->cmd_tbl.dac_load_detection)
> - return BP_RESULT_UNSUPPORTED;
> + bp_params.device_id = get_support_mask_for_device_id(
> + DEVICE_TYPE_CRT, engine_id == ENGINE_ID_DACB ? 2 : 1);
>
> if (bp_params.device_id == ATOM_DEVICE_CRT1_SUPPORT)
> device_id_mask = ATOM_S0_CRT1_MASK;
> @@ -815,7 +806,13 @@ static enum bp_result bios_parser_dac_load_detection(
> bios_0_scratch &= ~device_id_mask;
> dm_write_reg(ctx, bp->base.regs->BIOS_SCRATCH_0, bios_0_scratch);
>
> - bp_result = bp->cmd_tbl.dac_load_detection(bp, &bp_params);
> + if (engine_id == ENGINE_ID_DACA || engine_id == ENGINE_ID_DACB) {
> + if (!bp->cmd_tbl.dac_load_detection)
> + return BP_RESULT_UNSUPPORTED;
> +
> + bp_params.engine_id = engine_id;
> + bp_result = bp->cmd_tbl.dac_load_detection(bp, &bp_params);
> + }
>
> if (bp_result != BP_RESULT_OK)
> return bp_result;
> diff --git a/drivers/gpu/drm/amd/display/dc/dc_bios_types.h b/drivers/gpu/drm/amd/display/dc/dc_bios_types.h
> index 40d7a7d83c40..06fdde281a0c 100644
> --- a/drivers/gpu/drm/amd/display/dc/dc_bios_types.h
> +++ b/drivers/gpu/drm/amd/display/dc/dc_bios_types.h
> @@ -99,9 +99,7 @@ struct dc_vbios_funcs {
> struct bp_encoder_control *cntl);
> enum bp_result (*dac_load_detection)(
> struct dc_bios *bios,
> - enum engine_id engine_id,
> - enum dal_device_type device_type,
> - uint32_t enum_id);
> + enum engine_id engine_id);
> enum bp_result (*transmitter_control)(
> struct dc_bios *bios,
> struct bp_transmitter_control *cntl);
> diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c
> index 4659e1b489ba..4e820020252b 100644
> --- a/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c
> +++ b/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c
> @@ -674,6 +674,17 @@ dce110_dac_encoder_control(struct pipe_ctx *pipe_ctx, bool enable)
> bios->funcs->encoder_control(bios, &encoder_control);
> }
>
> +static bool
> +dce110_dac_load_detect(struct dc_link *link)
> +{
> + struct dc_bios *bios = link->ctx->dc_bios;
> + struct link_encoder *link_enc = link->link_enc;
> + enum bp_result bp_result = BP_RESULT_FAILURE;
Nitpick - bp_result is assigned below right away so it doesn't have to
be assigned here <-- complained by Coverity.
> +
> + bp_result = bios->funcs->dac_load_detection(bios, link_enc->analog_engine);
> + return bp_result == BP_RESULT_OK;
> +}
> +
> void dce110_enable_stream(struct pipe_ctx *pipe_ctx)
> {
> enum dc_lane_count lane_count =
> @@ -3442,6 +3453,7 @@ static const struct hw_sequencer_funcs dce110_funcs = {
> .enable_tmds_link_output = dce110_enable_tmds_link_output,
> .enable_dp_link_output = dce110_enable_dp_link_output,
> .disable_link_output = dce110_disable_link_output,
> + .dac_load_detect = dce110_dac_load_detect,
> };
>
> static const struct hwseq_private_funcs dce110_private_funcs = {
> diff --git a/drivers/gpu/drm/amd/display/dc/hwss/hw_sequencer.h b/drivers/gpu/drm/amd/display/dc/hwss/hw_sequencer.h
> index 51b0f0fd8fcd..5c9a758fde37 100644
> --- a/drivers/gpu/drm/amd/display/dc/hwss/hw_sequencer.h
> +++ b/drivers/gpu/drm/amd/display/dc/hwss/hw_sequencer.h
> @@ -1187,6 +1187,7 @@ struct hw_sequencer_funcs {
> void (*disable_link_output)(struct dc_link *link,
> const struct link_resource *link_res,
> enum signal_type signal);
> + bool (*dac_load_detect)(struct dc_link *link);
>
> void (*get_dcc_en_bits)(struct dc *dc, int *dcc_en_bits);
>
> diff --git a/drivers/gpu/drm/amd/display/dc/link/link_detection.c b/drivers/gpu/drm/amd/display/dc/link/link_detection.c
> index 578509e8d0e2..1585cce65b0e 100644
> --- a/drivers/gpu/drm/amd/display/dc/link/link_detection.c
> +++ b/drivers/gpu/drm/amd/display/dc/link/link_detection.c
> @@ -932,28 +932,10 @@ static bool link_detect_ddc_probe(struct dc_link *link)
> */
> static bool link_detect_dac_load_detect(struct dc_link *link)
> {
> - struct dc_bios *bios = link->ctx->dc_bios;
> - struct link_encoder *link_enc = link->link_enc;
> - enum engine_id engine_id = link_enc->preferred_engine;
> - enum dal_device_type device_type = DEVICE_TYPE_CRT;
> - enum bp_result bp_result = BP_RESULT_UNSUPPORTED;
> - uint32_t enum_id;
> -
> - switch (engine_id) {
> - case ENGINE_ID_DACB:
> - enum_id = 2;
> - break;
> - case ENGINE_ID_DACA:
> - default:
> - engine_id = ENGINE_ID_DACA;
> - enum_id = 1;
> - break;
> - }
> -
> - if (bios->funcs->dac_load_detection)
> - bp_result = bios->funcs->dac_load_detection(bios, engine_id, device_type, enum_id);
> + if (!link->dc->hwss.dac_load_detect)
> + return false;
>
> - return bp_result == BP_RESULT_OK;
> + return link->dc->hwss.dac_load_detect(link);
> }
>
> /*
next prev parent reply other threads:[~2026-01-30 20:01 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-26 21:08 [PATCH 00/14] drm/amd/display: Add support for external DP bridge encoders in DC Timur Kristóf
2026-01-26 21:08 ` [PATCH 01/14] drm/amd/display: Use DCE 6 link encoder for DCE 6 analog connectors Timur Kristóf
2026-01-26 21:08 ` [PATCH 02/14] drm/amd/display: Only use analog link encoder with analog engine Timur Kristóf
2026-01-26 21:08 ` [PATCH 03/14] drm/amd/display: Only use analog stream " Timur Kristóf
2026-01-26 21:08 ` [PATCH 04/14] drm/amd/display: Add color depth helper function to BIOS parser Timur Kristóf
2026-01-26 21:08 ` [PATCH 05/14] drm/amd/display: Refactor DAC load detection, move to HWSS Timur Kristóf
2026-01-30 20:00 ` Alex Hung [this message]
2026-01-26 21:08 ` [PATCH 06/14] drm/amd/display: Implement BIOS parser external encoder control Timur Kristóf
2026-01-26 21:08 ` [PATCH 07/14] drm/amd/display: Implement DDC probe over AUX channel Timur Kristóf
2026-01-30 19:53 ` Alex Hung
2026-01-26 21:08 ` [PATCH 08/14] drm/amd/display: Add ability for HWSS to prepare the DDC before use Timur Kristóf
2026-01-26 21:08 ` [PATCH 09/14] drm/amd/display: Use preferred DP link rate if specified Timur Kristóf
2026-01-26 21:08 ` [PATCH 10/14] drm/amd/display: Add DCE HWSS support for external DP bridge encoders Timur Kristóf
2026-01-26 21:08 ` [PATCH 11/14] drm/amd/display: Link detection " Timur Kristóf
2026-01-26 21:08 ` [PATCH 12/14] drm/amd/display: Use " Timur Kristóf
2026-01-26 21:08 ` [PATCH 13/14] drm/amd/display: Implement DAC load detection on " Timur Kristóf
2026-01-26 21:08 ` [PATCH 14/14] drm/amdgpu: Use DC by default on CIK APUs Timur Kristóf
2026-02-09 15:35 ` [PATCH 00/14] drm/amd/display: Add support for external DP bridge encoders in DC Rodrigo Siqueira
2026-02-09 18:12 ` Alex Hung
2026-02-09 22:10 ` Timur Kristóf
2026-02-09 23:14 ` Alex Hung
2026-02-16 4:33 ` Alex Hung
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=e1d478b2-99a4-40af-94c9-5eddc72a717b@amd.com \
--to=alex.hung@amd.com \
--cc=Alexander.Deucher@amd.com \
--cc=Christian.Koenig@amd.com \
--cc=Prike.Liang@amd.com \
--cc=Ray.Wu@amd.com \
--cc=amd-gfx@lists.freedesktop.org \
--cc=ivan.lipski@amd.com \
--cc=mario.limonciello@amd.com \
--cc=siqueira@igalia.com \
--cc=sunpeng.li@amd.com \
--cc=timur.kristof@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox