drm/nouveau/i2c/gf119-: add support for address-only transactions

Since switching the I2C-over-AUX helpers, there have been regressions on
some display combinations due to us not having support for "address only"
transactions.

This commits enables support for them for GF119 and newer.

Earlier GPUs have been reverted to a custom I2C-over-AUX algorithm.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_connector.c

@@ -1158,8 +1158,6 @@ nouveau_connector_aux_xfer(struct drm_dp_aux *obj, struct drm_dp_aux_msg *msg)
 		return -ENODEV;
 	if (WARN_ON(msg->size > 16))
 		return -E2BIG;
-	if (msg->size == 0)
-		return msg->size;
 
 	ret = nvkm_i2c_aux_acquire(aux);
 	if (ret)

drivers/gpu/drm/nouveau/nv50_display.c

@@ -3674,15 +3674,24 @@ nv50_sor_create(struct drm_connector *connector, struct dcb_output *dcbe)
 	drm_mode_connector_attach_encoder(connector, encoder);
 
 	if (dcbe->type == DCB_OUTPUT_DP) {
+		struct nv50_disp *disp = nv50_disp(encoder->dev);
 		struct nvkm_i2c_aux *aux =
 			nvkm_i2c_aux_find(i2c, dcbe->i2c_index);
 		if (aux) {
-			nv_encoder->i2c = &nv_connector->aux.ddc;
+			if (disp->disp->oclass < GF110_DISP) {
+				/* HW has no support for address-only
+				 * transactions, so we're required to
+				 * use custom I2C-over-AUX code.
+				 */
+				nv_encoder->i2c = &aux->i2c;
+			} else {
+				nv_encoder->i2c = &nv_connector->aux.ddc;
+			}
 			nv_encoder->aux = aux;
 		}
 
 		/*TODO: Use DP Info Table to check for support. */
-		if (nv50_disp(encoder->dev)->disp->oclass >= GF110_DISP) {
+		if (disp->disp->oclass >= GF110_DISP) {
 			ret = nv50_mstm_new(nv_encoder, &nv_connector->aux, 16,
 					    nv_connector->base.base.id,
 					    &nv_encoder->dp.mstm);

drivers/gpu/drm/nouveau/nvkm/subdev/i2c/Kbuild

@@ -25,6 +25,7 @@ nvkm-y += nvkm/subdev/i2c/bit.o
 
 nvkm-y += nvkm/subdev/i2c/aux.o
 nvkm-y += nvkm/subdev/i2c/auxg94.o
+nvkm-y += nvkm/subdev/i2c/auxgf119.o
 nvkm-y += nvkm/subdev/i2c/auxgm200.o
 
 nvkm-y += nvkm/subdev/i2c/anx9805.o

drivers/gpu/drm/nouveau/nvkm/subdev/i2c/aux.c

@@ -117,6 +117,10 @@ int
 nvkm_i2c_aux_xfer(struct nvkm_i2c_aux *aux, bool retry, u8 type,
 		  u32 addr, u8 *data, u8 *size)
 {
+	if (!*size && !aux->func->address_only) {
+		AUX_ERR(aux, "address-only transaction dropped");
+		return -ENOSYS;
+	}
 	return aux->func->xfer(aux, retry, type, addr, data, size);
 }
 

drivers/gpu/drm/nouveau/nvkm/subdev/i2c/aux.h

@@ -3,6 +3,7 @@
 #include "pad.h"
 
 struct nvkm_i2c_aux_func {
+	bool address_only;
 	int  (*xfer)(struct nvkm_i2c_aux *, bool retry, u8 type,
 		     u32 addr, u8 *data, u8 *size);
 	int  (*lnk_ctl)(struct nvkm_i2c_aux *, int link_nr, int link_bw,
@@ -17,7 +18,12 @@ void nvkm_i2c_aux_del(struct nvkm_i2c_aux **);
 int nvkm_i2c_aux_xfer(struct nvkm_i2c_aux *, bool retry, u8 type,
 		      u32 addr, u8 *data, u8 *size);
 
+int g94_i2c_aux_new_(const struct nvkm_i2c_aux_func *, struct nvkm_i2c_pad *,
+		     int, u8, struct nvkm_i2c_aux **);
+
 int g94_i2c_aux_new(struct nvkm_i2c_pad *, int, u8, struct nvkm_i2c_aux **);
+int g94_i2c_aux_xfer(struct nvkm_i2c_aux *, bool, u8, u32, u8 *, u8 *);
+int gf119_i2c_aux_new(struct nvkm_i2c_pad *, int, u8, struct nvkm_i2c_aux **);
 int gm200_i2c_aux_new(struct nvkm_i2c_pad *, int, u8, struct nvkm_i2c_aux **);
 
 #define AUX_MSG(b,l,f,a...) do {                                               \

drivers/gpu/drm/nouveau/nvkm/subdev/i2c/auxg94.c

@@ -72,7 +72,7 @@ g94_i2c_aux_init(struct g94_i2c_aux *aux)
 	return 0;
 }
 
-static int
+int
 g94_i2c_aux_xfer(struct nvkm_i2c_aux *obj, bool retry,
 		 u8 type, u32 addr, u8 *data, u8 *size)
 {
@@ -105,9 +105,9 @@ g94_i2c_aux_xfer(struct nvkm_i2c_aux *obj, bool retry,
 	}
 
 	ctrl  = nvkm_rd32(device, 0x00e4e4 + base);
-	ctrl &= ~0x0001f0ff;
+	ctrl &= ~0x0001f1ff;
 	ctrl |= type << 12;
-	ctrl |= *size - 1;
+	ctrl |= (*size ? (*size - 1) : 0x00000100);
 	nvkm_wr32(device, 0x00e4e0 + base, addr);
 
 	/* (maybe) retry transaction a number of times on failure... */
@@ -160,14 +160,10 @@ g94_i2c_aux_xfer(struct nvkm_i2c_aux *obj, bool retry,
 	return ret < 0 ? ret : (stat & 0x000f0000) >> 16;
 }
 
-static const struct nvkm_i2c_aux_func
-g94_i2c_aux_func = {
-	.xfer = g94_i2c_aux_xfer,
-};
-
 int
-g94_i2c_aux_new(struct nvkm_i2c_pad *pad, int index, u8 drive,
-		struct nvkm_i2c_aux **paux)
+g94_i2c_aux_new_(const struct nvkm_i2c_aux_func *func,
+		 struct nvkm_i2c_pad *pad, int index, u8 drive,
+		 struct nvkm_i2c_aux **paux)
 {
 	struct g94_i2c_aux *aux;
 
@@ -175,8 +171,20 @@ g94_i2c_aux_new(struct nvkm_i2c_pad *pad, int index, u8 drive,
 		return -ENOMEM;
 	*paux = &aux->base;
 
-	nvkm_i2c_aux_ctor(&g94_i2c_aux_func, pad, index, &aux->base);
+	nvkm_i2c_aux_ctor(func, pad, index, &aux->base);
 	aux->ch = drive;
 	aux->base.intr = 1 << aux->ch;
 	return 0;
 }
+
+static const struct nvkm_i2c_aux_func
+g94_i2c_aux = {
+	.xfer = g94_i2c_aux_xfer,
+};
+
+int
+g94_i2c_aux_new(struct nvkm_i2c_pad *pad, int index, u8 drive,
+		struct nvkm_i2c_aux **paux)
+{
+	return g94_i2c_aux_new_(&g94_i2c_aux, pad, index, drive, paux);
+}

drivers/gpu/drm/nouveau/nvkm/subdev/i2c/auxgf119.c

+/*
+ * Copyright 2017 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include "aux.h"
+
+static const struct nvkm_i2c_aux_func
+gf119_i2c_aux = {
+	.address_only = true,
+	.xfer = g94_i2c_aux_xfer,
+};
+
+int
+gf119_i2c_aux_new(struct nvkm_i2c_pad *pad, int index, u8 drive,
+		  struct nvkm_i2c_aux **paux)
+{
+	return g94_i2c_aux_new_(&gf119_i2c_aux, pad, index, drive, paux);
+}

drivers/gpu/drm/nouveau/nvkm/subdev/i2c/auxgm200.c

@@ -105,9 +105,9 @@ gm200_i2c_aux_xfer(struct nvkm_i2c_aux *obj, bool retry,
 	}
 
 	ctrl  = nvkm_rd32(device, 0x00d954 + base);
-	ctrl &= ~0x0001f0ff;
+	ctrl &= ~0x0001f1ff;
 	ctrl |= type << 12;
-	ctrl |= *size - 1;
+	ctrl |= (*size ? (*size - 1) : 0x00000100);
 	nvkm_wr32(device, 0x00d950 + base, addr);
 
 	/* (maybe) retry transaction a number of times on failure... */
@@ -162,6 +162,7 @@ gm200_i2c_aux_xfer(struct nvkm_i2c_aux *obj, bool retry,
 
 static const struct nvkm_i2c_aux_func
 gm200_i2c_aux_func = {
+	.address_only = true,
 	.xfer = gm200_i2c_aux_xfer,
 };
 

drivers/gpu/drm/nouveau/nvkm/subdev/i2c/padgf119.c

@@ -28,7 +28,7 @@
 static const struct nvkm_i2c_pad_func
 gf119_i2c_pad_s_func = {
 	.bus_new_4 = gf119_i2c_bus_new,
-	.aux_new_6 = g94_i2c_aux_new,
+	.aux_new_6 = gf119_i2c_aux_new,
 	.mode = g94_i2c_pad_mode,
 };
 
@@ -41,7 +41,7 @@ gf119_i2c_pad_s_new(struct nvkm_i2c *i2c, int id, struct nvkm_i2c_pad **ppad)
 static const struct nvkm_i2c_pad_func
 gf119_i2c_pad_x_func = {
 	.bus_new_4 = gf119_i2c_bus_new,
-	.aux_new_6 = g94_i2c_aux_new,
+	.aux_new_6 = gf119_i2c_aux_new,
 };
 
 int