target/linux/bcm27xx/patches-6.1/950-0034-drm-bridge-Introduce-pre_enable_upstream_first-to-al.patch

   1 From 5365030a003a6cb0c336202256341e4bc9d65d52 Mon Sep 17 00:00:00 2001
   2 From: Dave Stevenson <dave.stevenson@raspberrypi.com>
   3 Date: Thu, 16 Dec 2021 15:25:35 +0000
   4 Subject: [PATCH] drm/bridge: Introduce pre_enable_upstream_first to
   5  alter bridge init order
   6
   7 DSI sink devices typically want the DSI host powered up and configured
   8 before they are powered up. pre_enable is the place this would normally
   9 happen, but they are called in reverse order from panel/connector towards
  10 the encoder, which is the "wrong" order.
  11
  12 Add a new flag pre_enable_upstream_first that any bridge can set
  13 to swap the order of pre_enable (and post_disable) for that and the
  14 immediately upstream bridge.
  15 Should the immediately upstream bridge also set the
  16 pre_enable_upstream_first flag, the bridge upstream of that will be called
  17 before either of those which requested pre_enable_upstream_first.
  18
  19 eg:
  20 - Panel
  21 - Bridge 1
  22 - Bridge 2 pre_enable_upstream_first
  23 - Bridge 3
  24 - Bridge 4 pre_enable_upstream_first
  25 - Bridge 5 pre_enable_upstream_first
  26 - Bridge 6
  27 - Encoder
  28 Would result in pre_enable's being called as Panel, Bridge 1, Bridge 3,
  29 Bridge 2, Bridge 6, Bridge 5, Bridge 4, Encoder.
  30
  31 Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
  32 ---
  33  drivers/gpu/drm/drm_bridge.c | 177 +++++++++++++++++++++++++----------
  34  include/drm/drm_bridge.h     |   8 ++
  35  2 files changed, 137 insertions(+), 48 deletions(-)
  36
  37 --- a/drivers/gpu/drm/drm_bridge.c
  38 +++ b/drivers/gpu/drm/drm_bridge.c
  39 @@ -547,20 +547,15 @@ EXPORT_SYMBOL(drm_bridge_chain_disable);
  40   * encoder chain, starting from the first bridge to the last. These are called
  41   * after completing the encoder's prepare op.
  42   *
  43 + * If a bridge sets @pre_enable_upstream_first, then the @post_disable for that
  44 + * bridge will be called before the previous one to reverse the @pre_enable
  45 + * calling direction.
  46 + *
  47   * Note: the bridge passed should be the one closest to the encoder
  48   */
  49  void drm_bridge_chain_post_disable(struct drm_bridge *bridge)
  50  {
  51 -       struct drm_encoder *encoder;
  52 -
  53 -       if (!bridge)
  54 -               return;
  55 -
  56 -       encoder = bridge->encoder;
  57 -       list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
  58 -               if (bridge->funcs->post_disable)
  59 -                       bridge->funcs->post_disable(bridge);
  60 -       }
  61 +       drm_atomic_bridge_chain_post_disable(bridge, NULL);
  62  }
  63  EXPORT_SYMBOL(drm_bridge_chain_post_disable);
  64
  65 @@ -602,24 +597,14 @@ EXPORT_SYMBOL(drm_bridge_chain_mode_set)
  66   * chain, starting from the last bridge to the first. These are called
  67   * before calling the encoder's commit op.
  68   *
  69 + * If a bridge sets @pre_enable_upstream_first, then the @pre_enable for the
  70 + * previous bridge will be called before @pre_enable of this bridge.
  71 + *
  72   * Note: the bridge passed should be the one closest to the encoder
  73   */
  74  void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)
  75  {
  76 -       struct drm_encoder *encoder;
  77 -       struct drm_bridge *iter;
  78 -
  79 -       if (!bridge)
  80 -               return;
  81 -
  82 -       encoder = bridge->encoder;
  83 -       list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
  84 -               if (iter->funcs->pre_enable)
  85 -                       iter->funcs->pre_enable(iter);
  86 -
  87 -               if (iter == bridge)
  88 -                       break;
  89 -       }
  90 +       drm_atomic_bridge_chain_pre_enable(bridge, NULL);
  91  }
  92  EXPORT_SYMBOL(drm_bridge_chain_pre_enable);
  93
  94 @@ -691,6 +676,25 @@ void drm_atomic_bridge_chain_disable(str
  95  }
  96  EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
  97
  98 +static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
  99 +                                               struct drm_atomic_state *old_state)
 100 +{
 101 +       if (old_state && bridge->funcs->atomic_post_disable) {
 102 +               struct drm_bridge_state *old_bridge_state;
 103 +
 104 +               old_bridge_state =
 105 +                       drm_atomic_get_old_bridge_state(old_state,
 106 +                                                       bridge);
 107 +               if (WARN_ON(!old_bridge_state))
 108 +                       return;
 109 +
 110 +               bridge->funcs->atomic_post_disable(bridge,
 111 +                                                  old_bridge_state);
 112 +       } else if (bridge->funcs->post_disable) {
 113 +               bridge->funcs->post_disable(bridge);
 114 +       }
 115 +}
 116 +
 117  /**
 118   * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
 119   *                                       in the encoder chain
 120 @@ -701,6 +705,9 @@ EXPORT_SYMBOL(drm_atomic_bridge_chain_di
 121   * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
 122   * starting from the first bridge to the last. These are called after completing
 123   * &drm_encoder_helper_funcs.atomic_disable
 124 + * If a bridge sets @pre_enable_upstream_first, then the @post_disable for that
 125 + * bridge will be called before the previous one to reverse the @pre_enable
 126 + * calling direction.
 127   *
 128   * Note: the bridge passed should be the one closest to the encoder
 129   */
 130 @@ -708,30 +715,75 @@ void drm_atomic_bridge_chain_post_disabl
 131                                           struct drm_atomic_state *old_state)
 132  {
 133         struct drm_encoder *encoder;
 134 +       struct drm_bridge *next, *limit;
 135
 136         if (!bridge)
 137                 return;
 138
 139         encoder = bridge->encoder;
 140 +
 141         list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
 142 -               if (bridge->funcs->atomic_post_disable) {
 143 -                       struct drm_bridge_state *old_bridge_state;
 144 +               limit = NULL;
 145
 146 -                       old_bridge_state =
 147 -                               drm_atomic_get_old_bridge_state(old_state,
 148 -                                                               bridge);
 149 -                       if (WARN_ON(!old_bridge_state))
 150 -                               return;
 151 +               if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {
 152 +                       next = list_next_entry(bridge, chain_node);
 153
 154 -                       bridge->funcs->atomic_post_disable(bridge,
 155 -                                                          old_bridge_state);
 156 -               } else if (bridge->funcs->post_disable) {
 157 -                       bridge->funcs->post_disable(bridge);
 158 +                       if (next->pre_enable_upstream_first) {
 159 +                               /* Downstream bridge had requested that upstream
 160 +                                * was enabled first, so disabled last
 161 +                                */
 162 +                               limit = next;
 163 +
 164 +                               /* Find the next bridge that has NOT requested
 165 +                                * upstream to be enabled first / disabled last
 166 +                                */
 167 +                               list_for_each_entry_from(next, &encoder->bridge_chain,
 168 +                                                        chain_node) {
 169 +                                       if (next->pre_enable_upstream_first) {
 170 +                                               next = list_prev_entry(next, chain_node);
 171 +                                               limit = next;
 172 +                                               break;
 173 +                                       }
 174 +                               }
 175 +
 176 +                               /* Call these bridges in reverse order */
 177 +                               list_for_each_entry_from_reverse(next, &encoder->bridge_chain,
 178 +                                                                chain_node) {
 179 +                                       if (next == bridge)
 180 +                                               break;
 181 +
 182 +                                       drm_atomic_bridge_call_post_disable(next,
 183 +                                                                           old_state);
 184 +                               }
 185 +                       }
 186                 }
 187 +
 188 +               drm_atomic_bridge_call_post_disable(bridge, old_state);
 189 +
 190 +               if (limit)
 191 +                       bridge = limit;
 192         }
 193  }
 194  EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
 195
 196 +static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
 197 +                                             struct drm_atomic_state *old_state)
 198 +{
 199 +       if (old_state && bridge->funcs->atomic_pre_enable) {
 200 +               struct drm_bridge_state *old_bridge_state;
 201 +
 202 +               old_bridge_state =
 203 +                       drm_atomic_get_old_bridge_state(old_state,
 204 +                                                       bridge);
 205 +               if (WARN_ON(!old_bridge_state))
 206 +                       return;
 207 +
 208 +               bridge->funcs->atomic_pre_enable(bridge, old_bridge_state);
 209 +       } else if (bridge->funcs->pre_enable) {
 210 +               bridge->funcs->pre_enable(bridge);
 211 +       }
 212 +}
 213 +
 214  /**
 215   * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
 216   *                                     the encoder chain
 217 @@ -743,33 +795,62 @@ EXPORT_SYMBOL(drm_atomic_bridge_chain_po
 218   * starting from the last bridge to the first. These are called before calling
 219   * &drm_encoder_helper_funcs.atomic_enable
 220   *
 221 + * If a bridge sets @pre_enable_upstream_first, then the pre_enable for the
 222 + * upstream bridge will be called before pre_enable of this bridge.
 223 + *
 224   * Note: the bridge passed should be the one closest to the encoder
 225   */
 226  void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
 227                                         struct drm_atomic_state *old_state)
 228  {
 229         struct drm_encoder *encoder;
 230 -       struct drm_bridge *iter;
 231 +       struct drm_bridge *iter, *next, *limit;
 232
 233         if (!bridge)
 234                 return;
 235
 236         encoder = bridge->encoder;
 237 -       list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
 238 -               if (iter->funcs->atomic_pre_enable) {
 239 -                       struct drm_bridge_state *old_bridge_state;
 240
 241 -                       old_bridge_state =
 242 -                               drm_atomic_get_old_bridge_state(old_state,
 243 -                                                               iter);
 244 -                       if (WARN_ON(!old_bridge_state))
 245 -                               return;
 246 +       list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
 247 +               if (iter->pre_enable_upstream_first) {
 248 +                       next = iter;
 249 +                       limit = bridge;
 250 +                       list_for_each_entry_from_reverse(next,
 251 +                                                        &encoder->bridge_chain,
 252 +                                                        chain_node) {
 253 +                               if (next == bridge)
 254 +                                       break;
 255 +
 256 +                               if (!next->pre_enable_upstream_first) {
 257 +                                       /* Found first bridge that does NOT
 258 +                                        * request upstream to be enabled first
 259 +                                        */
 260 +                                       limit = list_prev_entry(next, chain_node);
 261 +                                       break;
 262 +                               }
 263 +                       }
 264 +
 265 +                       list_for_each_entry_from(next, &encoder->bridge_chain, chain_node) {
 266 +                               /* Call requested upstream bridge pre_enable
 267 +                                * in order.
 268 +                                */
 269 +                               if (next == iter)
 270 +                                       /* At the first bridgge to request upstream
 271 +                                        * bridges called first.
 272 +                                        */
 273 +                                       break;
 274
 275 -                       iter->funcs->atomic_pre_enable(iter, old_bridge_state);
 276 -               } else if (iter->funcs->pre_enable) {
 277 -                       iter->funcs->pre_enable(iter);
 278 +                               drm_atomic_bridge_call_pre_enable(next, old_state);
 279 +                       }
 280                 }
 281
 282 +               drm_atomic_bridge_call_pre_enable(iter, old_state);
 283 +
 284 +               if (iter->pre_enable_upstream_first)
 285 +                       /* Jump all bridges that we have already pre_enabled
 286 +                        */
 287 +                       iter = limit;
 288 +
 289                 if (iter == bridge)
 290                         break;
 291         }
 292 --- a/include/drm/drm_bridge.h
 293 +++ b/include/drm/drm_bridge.h
 294 @@ -769,6 +769,14 @@ struct drm_bridge {
 295          */
 296         bool interlace_allowed;
 297         /**
 298 +        * @pre_enable_upstream_first: The bridge requires that the upstream
 299 +        * bridge @pre_enable function is called before its @pre_enable,
 300 +        * and conversely for post_disable. This is most frequently a
 301 +        * requirement for DSI devices which need the host to be initialised
 302 +        * before the peripheral.
 303 +        */
 304 +       bool pre_enable_upstream_first;
 305 +       /**
 306          * @ddc: Associated I2C adapter for DDC access, if any.
 307          */
 308         struct i2c_adapter *ddc;