Re: [PATCH] drm/i915/ddi: abstract figuring out encoder name

[Nautiyal, Ankit K]

On 9/3/2025 3:40 PM, Jani Nikula wrote:

The encoder name deduction has become a bit cumbersome within
intel_ddi_init(). Split it out to a separate function to declutter
intel_ddi_init(), even if that means having to use a temp seq buffer for
the name.

Cc: Ankit Nautiyal <ankit.k.nauti...@intel.com>
Signed-off-by: Jani Nikula <jani.nik...@intel.com>

LGTM.

Reviewed-by: Ankit Nautiyal <ankit.k.nauti...@intel.com>

---
  drivers/gpu/drm/i915/display/intel_ddi.c | 69 +++++++++++++-----------
  1 file changed, 38 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c 
b/drivers/gpu/drm/i915/display/intel_ddi.c
index 4e4ea3a0ff83..68e049ad042b 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -26,6 +26,7 @@
   */

#include <linux/iopoll.h>

+#include <linux/seq_buf.h>
  #include <linux/string_helpers.h>

#include <drm/display/drm_dp_helper.h>

@@ -5077,11 +5078,45 @@ static bool port_in_use(struct intel_display *display, 
enum port port)
        return false;
  }

+static const char *intel_ddi_encoder_name(struct intel_display *display,

+                                         enum port port, enum phy phy,
+                                         struct seq_buf *s)
+{
+       if (DISPLAY_VER(display) >= 13 && port >= PORT_D_XELPD) {
+               seq_buf_printf(s, "DDI %c/PHY %c",
+                              port_name(port - PORT_D_XELPD + PORT_D),
+                              phy_name(phy));
+       } else if (DISPLAY_VER(display) >= 12) {
+               enum tc_port tc_port = intel_port_to_tc(display, port);
+
+               seq_buf_printf(s, "DDI %s%c/PHY %s%c",
+                              port >= PORT_TC1 ? "TC" : "",
+                              port >= PORT_TC1 ? port_tc_name(port) : 
port_name(port),
+                              tc_port != TC_PORT_NONE ? "TC" : "",
+                              tc_port != TC_PORT_NONE ? tc_port_name(tc_port) 
: phy_name(phy));
+       } else if (DISPLAY_VER(display) >= 11) {
+               enum tc_port tc_port = intel_port_to_tc(display, port);
+
+               seq_buf_printf(s, "DDI %c%s/PHY %s%c",
+                              port_name(port),
+                              port >= PORT_C ? " (TC)" : "",
+                              tc_port != TC_PORT_NONE ? "TC" : "",
+                              tc_port != TC_PORT_NONE ? tc_port_name(tc_port) 
: phy_name(phy));
+       } else {
+               seq_buf_printf(s, "DDI %c/PHY %c", port_name(port),  
phy_name(phy));
+       }
+
+       drm_WARN_ON(display->drm, seq_buf_has_overflowed(s));
+
+       return seq_buf_str(s);
+}
+
  void intel_ddi_init(struct intel_display *display,
                    const struct intel_bios_encoder_data *devdata)
  {
        struct intel_digital_port *dig_port;
        struct intel_encoder *encoder;
+       DECLARE_SEQ_BUF(encoder_name, 20);
        bool init_hdmi, init_dp;
        enum port port;
        enum phy phy;
@@ -5166,37 +5201,9 @@ void intel_ddi_init(struct intel_display *display,
        encoder = &dig_port->base;
        encoder->devdata = devdata;

- if (DISPLAY_VER(display) >= 13 && port >= PORT_D_XELPD) {

-               drm_encoder_init(display->drm, &encoder->base, &intel_ddi_funcs,
-                                DRM_MODE_ENCODER_TMDS,
-                                "DDI %c/PHY %c",
-                                port_name(port - PORT_D_XELPD + PORT_D),
-                                phy_name(phy));
-       } else if (DISPLAY_VER(display) >= 12) {
-               enum tc_port tc_port = intel_port_to_tc(display, port);
-
-               drm_encoder_init(display->drm, &encoder->base, &intel_ddi_funcs,
-                                DRM_MODE_ENCODER_TMDS,
-                                "DDI %s%c/PHY %s%c",
-                                port >= PORT_TC1 ? "TC" : "",
-                                port >= PORT_TC1 ? port_tc_name(port) : 
port_name(port),
-                                tc_port != TC_PORT_NONE ? "TC" : "",
-                                tc_port != TC_PORT_NONE ? 
tc_port_name(tc_port) : phy_name(phy));
-       } else if (DISPLAY_VER(display) >= 11) {
-               enum tc_port tc_port = intel_port_to_tc(display, port);
-
-               drm_encoder_init(display->drm, &encoder->base, &intel_ddi_funcs,
-                                DRM_MODE_ENCODER_TMDS,
-                                "DDI %c%s/PHY %s%c",
-                                port_name(port),
-                                port >= PORT_C ? " (TC)" : "",
-                                tc_port != TC_PORT_NONE ? "TC" : "",
-                                tc_port != TC_PORT_NONE ? 
tc_port_name(tc_port) : phy_name(phy));
-       } else {
-               drm_encoder_init(display->drm, &encoder->base, &intel_ddi_funcs,
-                                DRM_MODE_ENCODER_TMDS,
-                                "DDI %c/PHY %c", port_name(port), 
phy_name(phy));
-       }
+       drm_encoder_init(display->drm, &encoder->base, &intel_ddi_funcs,
+                        DRM_MODE_ENCODER_TMDS, "%s",
+                        intel_ddi_encoder_name(display, port, phy, 
&encoder_name));

intel_encoder_link_check_init(encoder, intel_ddi_link_check);