drm/tidss: Move OLDI mode validation to OLDI bridge mode_valid hook

After integrating OLDI support[0], it is necessary to identify which VP
instances use OLDI, since the OLDI driver owns the video port clock
(as a serial clock). Clock operations on these VPs must be delegated to
the OLDI driver, not handled by the TIDSS driver. This issue also
emerged in upstream discussions when DSI-related clock management was
attempted in the TIDSS driver[1].

To address this, add an 'is_ext_vp_clk' array to the 'tidss_device'
structure, marking a VP as 'true' during 'tidss_oldi_init()' and as
'false' during 'tidss_oldi_deinit()'. TIDSS then uses 'is_ext_vp_clk'
to skip clock validation checks in 'dispc_vp_mode_valid()' for VPs
under OLDI control.

Since OLDI uses the DSS VP clock directly as a serial interface and
manages its own rate, mode validation should be implemented in the OLDI
bridge's 'mode_valid' hook. This patch adds that logic, ensuring proper
delegation and avoiding spurious clock handling in the TIDSS driver.

[0]: https://lore.kernel.org/all/20250528122544.817829-1-aradhya.bhatia@linux.dev/
[1]: https://lore.kernel.org/all/DA6TT575Z82D.3MPK8HG5GRL8U@kernel.org/

Fixes: 7246e0929945 ("drm/tidss: Add OLDI bridge support")
Tested-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Swamil Jain <s-jain1@ti.com>
Link: https://patch.msgid.link/20251104151422.307162-3-s-jain1@ti.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patch.msgid.link/ffd5ebe03391b3c01e616c0c844a4b8ddecede36.1762513240.git.jani.nikula@intel.com

diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index 644b68185f67733f5fc7d90b08b936ce60740f68..58d5eb033bdbbf0ffe21001761ed4ea3683878bb 100644 (file)
--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -1306,6 +1306,13 @@ static int check_pixel_clock(struct dispc_device *dispc, u32 hw_videoport,
 {
        unsigned long round_clock;
 
+       /*
+        * For VP's with external clocking, clock operations must be
+        * delegated to respective driver, so we skip the check here.
+        */
+       if (dispc->tidss->is_ext_vp_clk[hw_videoport])
+               return 0;
+
        round_clock = clk_round_rate(dispc->vp_clk[hw_videoport], clock);
        /*
         * To keep the check consistent with dispc_vp_set_clk_rate(), we

diff --git a/drivers/gpu/drm/tidss/tidss_drv.h b/drivers/gpu/drm/tidss/tidss_drv.h
index 84454a4855d1151a7c3ccfa212f7273d42c5838f..e1c1f41d8b4beb0cb97f3ab58de6c01c4cc3835a 100644 (file)
--- a/drivers/gpu/drm/tidss/tidss_drv.h
+++ b/drivers/gpu/drm/tidss/tidss_drv.h
@@ -24,6 +24,8 @@ struct tidss_device {
 
        const struct dispc_features *feat;
        struct dispc_device *dispc;
+       bool is_ext_vp_clk[TIDSS_MAX_PORTS];
+
 
        unsigned int num_crtcs;
        struct drm_crtc *crtcs[TIDSS_MAX_PORTS];

diff --git a/drivers/gpu/drm/tidss/tidss_oldi.c b/drivers/gpu/drm/tidss/tidss_oldi.c
index 7688251beba280cdacfeeb2956560aba742faa56..17c535bfa05765ad9ff774b259e35a1cb377f047 100644 (file)
--- a/drivers/gpu/drm/tidss/tidss_oldi.c
+++ b/drivers/gpu/drm/tidss/tidss_oldi.c
@@ -309,6 +309,25 @@ static u32 *tidss_oldi_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
        return input_fmts;
 }
 
+static enum drm_mode_status
+tidss_oldi_mode_valid(struct drm_bridge *bridge,
+                     const struct drm_display_info *info,
+                     const struct drm_display_mode *mode)
+{
+       struct tidss_oldi *oldi = drm_bridge_to_tidss_oldi(bridge);
+       unsigned long round_clock;
+
+       round_clock = clk_round_rate(oldi->serial, mode->clock * 7 * 1000);
+       /*
+        * To keep the check consistent with dispc_vp_set_clk_rate(),
+        * we use the same 5% check here.
+        */
+       if (dispc_pclk_diff(mode->clock * 7 * 1000, round_clock) > 5)
+               return -EINVAL;
+
+       return 0;
+}
+
 static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = {
        .attach = tidss_oldi_bridge_attach,
        .atomic_pre_enable = tidss_oldi_atomic_pre_enable,
@@ -317,6 +336,7 @@ static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = {
        .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
        .atomic_reset = drm_atomic_helper_bridge_reset,
+       .mode_valid = tidss_oldi_mode_valid,
 };
 
 static int get_oldi_mode(struct device_node *oldi_tx, int *companion_instance)
@@ -430,6 +450,7 @@ void tidss_oldi_deinit(struct tidss_device *tidss)
        for (int i = 0; i < tidss->num_oldis; i++) {
                if (tidss->oldis[i]) {
                        drm_bridge_remove(&tidss->oldis[i]->bridge);
+                       tidss->is_ext_vp_clk[tidss->oldis[i]->parent_vp] = false;
                        tidss->oldis[i] = NULL;
                }
        }
@@ -580,6 +601,7 @@ int tidss_oldi_init(struct tidss_device *tidss)
                oldi->bridge.timings = &default_tidss_oldi_timings;
 
                tidss->oldis[tidss->num_oldis++] = oldi;
+               tidss->is_ext_vp_clk[oldi->parent_vp] = true;
                oldi->tidss = tidss;
 
                drm_bridge_add(&oldi->bridge);