gpu: host1x: Reserve VBLANK syncpoints at initialization

On T20-T148 chips, the bootloader can set up a boot splash
screen with DC configured to increment syncpoint 26/27
at VBLANK. Because of this we shouldn't allow these syncpoints
to be allocated until DC has been reset and will no longer
increment them in the background.

As such, on these chips, reserve those two syncpoints at
initialization, and only mark them free once the DC
driver has indicated it's safe to do so.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index cfda71e151cc2642bcaa567bf4d35016b58bbe0b..40bf8f33a2ae3b3aac301dc4effcb7f9416a0bae 100644 (file)
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -2045,6 +2045,12 @@ static int tegra_dc_init(struct host1x_client *client)
        struct drm_plane *cursor = NULL;
        int err;
 
+       /*
+        * DC has been reset by now, so VBLANK syncpoint can be released
+        * for general use.
+        */
+       host1x_syncpt_release_vblank_reservation(client, 26 + dc->pipe);
+
        /*
         * XXX do not register DCs with no window groups because we cannot
         * assign a primary plane to them, which in turn will cause KMS to

diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index d0ebb70e2fdd6e56750db8a0772b8491f8b7bf54..fbb6447b8659ed704564f33fe123d7975166bfe0 100644 (file)
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -77,6 +77,7 @@ static const struct host1x_info host1x01_info = {
        .has_hypervisor = false,
        .num_sid_entries = 0,
        .sid_table = NULL,
+       .reserve_vblank_syncpts = true,
 };
 
 static const struct host1x_info host1x02_info = {
@@ -91,6 +92,7 @@ static const struct host1x_info host1x02_info = {
        .has_hypervisor = false,
        .num_sid_entries = 0,
        .sid_table = NULL,
+       .reserve_vblank_syncpts = true,
 };
 
 static const struct host1x_info host1x04_info = {
@@ -105,6 +107,7 @@ static const struct host1x_info host1x04_info = {
        .has_hypervisor = false,
        .num_sid_entries = 0,
        .sid_table = NULL,
+       .reserve_vblank_syncpts = false,
 };
 
 static const struct host1x_info host1x05_info = {
@@ -119,6 +122,7 @@ static const struct host1x_info host1x05_info = {
        .has_hypervisor = false,
        .num_sid_entries = 0,
        .sid_table = NULL,
+       .reserve_vblank_syncpts = false,
 };
 
 static const struct host1x_sid_entry tegra186_sid_table[] = {
@@ -142,6 +146,7 @@ static const struct host1x_info host1x06_info = {
        .has_hypervisor = true,
        .num_sid_entries = ARRAY_SIZE(tegra186_sid_table),
        .sid_table = tegra186_sid_table,
+       .reserve_vblank_syncpts = false,
 };
 
 static const struct host1x_sid_entry tegra194_sid_table[] = {
@@ -165,6 +170,7 @@ static const struct host1x_info host1x07_info = {
        .has_hypervisor = true,
        .num_sid_entries = ARRAY_SIZE(tegra194_sid_table),
        .sid_table = tegra194_sid_table,
+       .reserve_vblank_syncpts = false,
 };
 
 static const struct of_device_id host1x_of_match[] = {

diff --git a/drivers/gpu/host1x/dev.h b/drivers/gpu/host1x/dev.h
index 63010ae37a9721ac6894216378d00cb0b6842440..fa6d4bc46e981c6b2d25780ab0a8d6e16f532f61 100644 (file)
--- a/drivers/gpu/host1x/dev.h
+++ b/drivers/gpu/host1x/dev.h
@@ -101,6 +101,12 @@ struct host1x_info {
        bool has_hypervisor; /* has hypervisor registers */
        unsigned int num_sid_entries;
        const struct host1x_sid_entry *sid_table;
+       /*
+        * On T20-T148, the boot chain may setup DC to increment syncpoints
+        * 26/27 on VBLANK. As such we cannot use these syncpoints until
+        * the display driver disables VBLANK increments.
+        */
+       bool reserve_vblank_syncpts;
 };
 
 struct host1x {

diff --git a/drivers/gpu/host1x/syncpt.c b/drivers/gpu/host1x/syncpt.c
index 877c5ab40cbdd76d6ec18fbb1e9fd0bba762b829..e648ebbb2027b3f1ad8bc123f71a07f096c1bdaa 100644 (file)
--- a/drivers/gpu/host1x/syncpt.c
+++ b/drivers/gpu/host1x/syncpt.c
@@ -67,7 +67,7 @@ struct host1x_syncpt *host1x_syncpt_alloc(struct host1x *host,
 
        mutex_lock(&host->syncpt_mutex);
 
-       for (i = 0; i < host->info->nb_pts && sp->name; i++, sp++)
+       for (i = 0; i < host->info->nb_pts && kref_read(&sp->ref); i++, sp++)
                ;
 
        if (i >= host->info->nb_pts)
@@ -374,6 +374,11 @@ int host1x_syncpt_init(struct host1x *host)
        if (!host->nop_sp)
                return -ENOMEM;
 
+       if (host->info->reserve_vblank_syncpts) {
+               kref_init(&host->syncpt[26].ref);
+               kref_init(&host->syncpt[27].ref);
+       }
+
        return 0;
 }
 
@@ -559,3 +564,31 @@ u32 host1x_syncpt_base_id(struct host1x_syncpt_base *base)
        return base->id;
 }
 EXPORT_SYMBOL(host1x_syncpt_base_id);
+
+static void do_nothing(struct kref *ref)
+{
+}
+
+/**
+ * host1x_syncpt_release_vblank_reservation() - Make VBLANK syncpoint
+ *   available for allocation
+ *
+ * @client: host1x bus client
+ * @syncpt_id: syncpoint ID to make available
+ *
+ * Makes VBLANK<i> syncpoint available for allocatation if it was
+ * reserved at initialization time. This should be called by the display
+ * driver after it has ensured that any VBLANK increment programming configured
+ * by the boot chain has been disabled.
+ */
+void host1x_syncpt_release_vblank_reservation(struct host1x_client *client,
+                                             u32 syncpt_id)
+{
+       struct host1x *host = dev_get_drvdata(client->host->parent);
+
+       if (!host->info->reserve_vblank_syncpts)
+               return;
+
+       kref_put(&host->syncpt[syncpt_id].ref, do_nothing);
+}
+EXPORT_SYMBOL(host1x_syncpt_release_vblank_reservation);

diff --git a/include/linux/host1x.h b/include/linux/host1x.h
index 107aea29bccbdbb390a6389e9095dc615835531e..e0a41c2b4c7a63e141b9836e34ac3a1b17589f51 100644 (file)
--- a/include/linux/host1x.h
+++ b/include/linux/host1x.h
@@ -163,6 +163,9 @@ struct host1x_syncpt *host1x_syncpt_alloc(struct host1x *host,
 struct host1x_syncpt_base *host1x_syncpt_get_base(struct host1x_syncpt *sp);
 u32 host1x_syncpt_base_id(struct host1x_syncpt_base *base);
 
+void host1x_syncpt_release_vblank_reservation(struct host1x_client *client,
+                                             u32 syncpt_id);
+
 /*
  * host1x channel
  */