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drm/tegra: sor - Protect CRC debugfs against enable state
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Accessing the CRC debugfs file will hang the system if the SOR is not
enabled, so make sure that it is stays enabled until the CRC has been
read.

Signed-off-by: Thierry Reding <treding@nvidia.com>
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Thierry Reding committed Jun 5, 2014
1 parent 76245ad commit 86f5c52
Showing 1 changed file with 45 additions and 24 deletions.
69 changes: 45 additions & 24 deletions drivers/gpu/drm/tegra/sor.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@ struct tegra_sor {

struct tegra_dpaux *dpaux;

struct mutex lock;
bool enabled;

struct dentry *debugfs;
Expand Down Expand Up @@ -299,14 +300,16 @@ static int tegra_output_sor_enable(struct tegra_output *output)
unsigned int vbe, vse, hbe, hse, vbs, hbs, i;
struct tegra_sor *sor = to_sor(output);
unsigned long value;
int err;
int err = 0;

mutex_lock(&sor->lock);

if (sor->enabled)
return 0;
goto unlock;

err = clk_prepare_enable(sor->clk);
if (err < 0)
return err;
goto unlock;

reset_control_deassert(sor->rst);

Expand Down Expand Up @@ -388,7 +391,7 @@ static int tegra_output_sor_enable(struct tegra_output *output)
err = tegra_io_rail_power_on(TEGRA_IO_RAIL_LVDS);
if (err < 0) {
dev_err(sor->dev, "failed to power on I/O rail: %d\n", err);
return err;
goto unlock;
}

usleep_range(5, 100);
Expand Down Expand Up @@ -512,21 +515,21 @@ static int tegra_output_sor_enable(struct tegra_output *output)
if (err < 0) {
dev_err(sor->dev, "failed to probe eDP link: %d\n",
err);
return err;
goto unlock;
}

err = drm_dp_link_power_up(aux, &link);
if (err < 0) {
dev_err(sor->dev, "failed to power up eDP link: %d\n",
err);
return err;
goto unlock;
}

err = drm_dp_link_configure(aux, &link);
if (err < 0) {
dev_err(sor->dev, "failed to configure eDP link: %d\n",
err);
return err;
goto unlock;
}

rate = drm_dp_link_rate_to_bw_code(link.rate);
Expand Down Expand Up @@ -561,7 +564,7 @@ static int tegra_output_sor_enable(struct tegra_output *output)
if (err < 0) {
dev_err(sor->dev, "DP fast link training failed: %d\n",
err);
return err;
goto unlock;
}

dev_dbg(sor->dev, "fast link training succeeded\n");
Expand All @@ -570,7 +573,7 @@ static int tegra_output_sor_enable(struct tegra_output *output)
err = tegra_sor_power_up(sor, 250);
if (err < 0) {
dev_err(sor->dev, "failed to power up SOR: %d\n", err);
return err;
goto unlock;
}

/* start display controller in continuous mode */
Expand Down Expand Up @@ -635,7 +638,7 @@ static int tegra_output_sor_enable(struct tegra_output *output)
err = tegra_sor_setup_pwm(sor, 250);
if (err < 0) {
dev_err(sor->dev, "failed to setup PWM: %d\n", err);
return err;
goto unlock;
}

value = tegra_dc_readl(dc, DC_DISP_DISP_WIN_OPTIONS);
Expand All @@ -647,18 +650,20 @@ static int tegra_output_sor_enable(struct tegra_output *output)
err = tegra_sor_attach(sor);
if (err < 0) {
dev_err(sor->dev, "failed to attach SOR: %d\n", err);
return err;
goto unlock;
}

err = tegra_sor_wakeup(sor);
if (err < 0) {
dev_err(sor->dev, "failed to enable DC: %d\n", err);
return err;
goto unlock;
}

sor->enabled = true;

return 0;
unlock:
mutex_unlock(&sor->lock);
return err;
}

static int tegra_sor_detach(struct tegra_sor *sor)
Expand Down Expand Up @@ -786,15 +791,17 @@ static int tegra_output_sor_disable(struct tegra_output *output)
struct tegra_dc *dc = to_tegra_dc(output->encoder.crtc);
struct tegra_sor *sor = to_sor(output);
unsigned long value;
int err;
int err = 0;

mutex_lock(&sor->lock);

if (!sor->enabled)
return 0;
goto unlock;

err = tegra_sor_detach(sor);
if (err < 0) {
dev_err(sor->dev, "failed to detach SOR: %d\n", err);
return err;
goto unlock;
}

tegra_sor_writel(sor, 0, SOR_STATE_1);
Expand Down Expand Up @@ -835,29 +842,31 @@ static int tegra_output_sor_disable(struct tegra_output *output)
err = tegra_sor_power_down(sor);
if (err < 0) {
dev_err(sor->dev, "failed to power down SOR: %d\n", err);
return err;
goto unlock;
}

if (sor->dpaux) {
err = tegra_dpaux_disable(sor->dpaux);
if (err < 0) {
dev_err(sor->dev, "failed to disable DP: %d\n", err);
return err;
goto unlock;
}
}

err = tegra_io_rail_power_off(TEGRA_IO_RAIL_LVDS);
if (err < 0) {
dev_err(sor->dev, "failed to power off I/O rail: %d\n", err);
return err;
goto unlock;
}

reset_control_assert(sor->rst);
clk_disable_unprepare(sor->clk);

sor->enabled = false;

return 0;
unlock:
mutex_unlock(&sor->lock);
return err;
}

static int tegra_output_sor_setup_clock(struct tegra_output *output,
Expand Down Expand Up @@ -952,10 +961,16 @@ static ssize_t tegra_sor_crc_read(struct file *file, char __user *buffer,
size_t size, loff_t *ppos)
{
struct tegra_sor *sor = file->private_data;
ssize_t num, err;
char buf[10];
ssize_t num;
u32 value;
int err;

mutex_lock(&sor->lock);

if (!sor->enabled) {
err = -EAGAIN;
goto unlock;
}

value = tegra_sor_readl(sor, SOR_STATE_1);
value &= ~SOR_STATE_ASY_CRC_MODE_MASK;
Expand All @@ -971,14 +986,18 @@ static ssize_t tegra_sor_crc_read(struct file *file, char __user *buffer,

err = tegra_sor_crc_wait(sor, 100);
if (err < 0)
return err;
goto unlock;

tegra_sor_writel(sor, SOR_CRC_A_RESET, SOR_CRC_A);
value = tegra_sor_readl(sor, SOR_CRC_B);

num = scnprintf(buf, sizeof(buf), "%08x\n", value);

return simple_read_from_buffer(buffer, size, ppos, buf, num);
err = simple_read_from_buffer(buffer, size, ppos, buf, num);

unlock:
mutex_unlock(&sor->lock);
return err;
}

static const struct file_operations tegra_sor_crc_fops = {
Expand Down Expand Up @@ -1168,6 +1187,8 @@ static int tegra_sor_probe(struct platform_device *pdev)
sor->client.ops = &sor_client_ops;
sor->client.dev = &pdev->dev;

mutex_init(&sor->lock);

err = host1x_client_register(&sor->client);
if (err < 0) {
dev_err(&pdev->dev, "failed to register host1x client: %d\n",
Expand Down

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