| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20180727151121.12296-1-enric.balletbo@collabora.com>
Date: Fri, 27 Jul 2018 17:11:21 +0200
From: Enric Balletbo i Serra <enric.balletbo@...labora.com>
To: linux-kernel@...r.kernel.org
Cc: kernel@...labora.com, cl@...k-chips.com, linux-pwm@...r.kernel.org,
linux-fbdev@...r.kernel.org,
Daniel Thompson <daniel.thompson@...aro.org>,
Thierry Reding <thierry.reding@...il.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
dri-devel@...ts.freedesktop.org, Jingoo Han <jingoohan1@...il.com>,
Lee Jones <lee.jones@...aro.org>
Subject: [PATCH v2] backlight: pwm_bl: switch to using "atomic" PWM API
The "atomic" API allows us to configure PWM period and duty_cycle and
enable it in one call.
The patch also moves the pwm_init_state just before any use of the
pwm_state struct, this fixes a potential bug where pwm_get_state
can be called before pwm_init_state.
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
---
Changes in v2:
- Do not force the PWM be off in the first call to pwm_apply_state.
- Delayed applying the state until we know what the period is.
- Removed pb->period as after the conversion is not needed.
drivers/video/backlight/pwm_bl.c | 71 ++++++++++++++++++--------------
1 file changed, 41 insertions(+), 30 deletions(-)
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index bdfcc0a71db1..dd1cb29b5332 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -28,7 +28,6 @@
struct pwm_bl_data {
struct pwm_device *pwm;
struct device *dev;
- unsigned int period;
unsigned int lth_brightness;
unsigned int *levels;
bool enabled;
@@ -46,7 +45,8 @@ struct pwm_bl_data {
void (*exit)(struct device *);
};
-static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
+static void pwm_backlight_power_on(struct pwm_bl_data *pb,
+ struct pwm_state *state)
{
int err;
@@ -57,7 +57,8 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
if (err < 0)
dev_err(pb->dev, "failed to enable power supply\n");
- pwm_enable(pb->pwm);
+ state->enabled = true;
+ pwm_apply_state(pb->pwm, state);
if (pb->post_pwm_on_delay)
msleep(pb->post_pwm_on_delay);
@@ -70,6 +71,8 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
static void pwm_backlight_power_off(struct pwm_bl_data *pb)
{
+ struct pwm_state state;
+
if (!pb->enabled)
return;
@@ -79,8 +82,10 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
if (pb->pwm_off_delay)
msleep(pb->pwm_off_delay);
- pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
+ pwm_get_state(pb->pwm, &state);
+ state.enabled = false;
+ state.duty_cycle = 0;
+ pwm_apply_state(pb->pwm, &state);
regulator_disable(pb->power_supply);
pb->enabled = false;
@@ -89,14 +94,17 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
{
unsigned int lth = pb->lth_brightness;
+ struct pwm_state state;
u64 duty_cycle;
+ pwm_get_state(pb->pwm, &state);
+
if (pb->levels)
duty_cycle = pb->levels[brightness];
else
duty_cycle = brightness;
- duty_cycle *= pb->period - lth;
+ duty_cycle *= state.period - lth;
do_div(duty_cycle, pb->scale);
return duty_cycle + lth;
@@ -106,6 +114,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = bl_get_data(bl);
int brightness = bl->props.brightness;
+ struct pwm_state state;
int duty_cycle;
if (bl->props.power != FB_BLANK_UNBLANK ||
@@ -118,8 +127,12 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
if (brightness > 0) {
duty_cycle = compute_duty_cycle(pb, brightness);
- pwm_config(pb->pwm, duty_cycle, pb->period);
- pwm_backlight_power_on(pb, brightness);
+ pwm_get_state(pb->pwm, &state);
+ state.duty_cycle = duty_cycle;
+ if (!state.enabled)
+ pwm_backlight_power_on(pb, &state);
+ else
+ pwm_apply_state(pb->pwm, &state);
} else
pwm_backlight_power_off(pb);
@@ -447,7 +460,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
struct device_node *node = pdev->dev.of_node;
struct pwm_bl_data *pb;
struct pwm_state state;
- struct pwm_args pargs;
unsigned int i;
int ret;
@@ -539,10 +551,26 @@ static int pwm_backlight_probe(struct platform_device *pdev)
dev_dbg(&pdev->dev, "got pwm for backlight\n");
- if (!data->levels) {
- /* Get the PWM period (in nanoseconds) */
- pwm_get_state(pb->pwm, &state);
+ /* Sync up PWM state. */
+ pwm_init_state(pb->pwm, &state);
+
+ /*
+ * The DT case will set the pwm_period_ns field to 0 and store the
+ * period, parsed from the DT, in the PWM device. For the non-DT case,
+ * set the period from platform data if it has not already been set
+ * via the PWM lookup table.
+ */
+ if (!state.period && (data->pwm_period_ns > 0))
+ state.period = data->pwm_period_ns;
+ ret = pwm_apply_state(pb->pwm, &state);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
+ ret);
+ goto err_alloc;
+ }
+
+ if (!data->levels) {
ret = pwm_backlight_brightness_default(&pdev->dev, data,
state.period);
if (ret < 0) {
@@ -559,24 +587,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
pb->levels = data->levels;
}
- /*
- * FIXME: pwm_apply_args() should be removed when switching to
- * the atomic PWM API.
- */
- pwm_apply_args(pb->pwm);
-
- /*
- * The DT case will set the pwm_period_ns field to 0 and store the
- * period, parsed from the DT, in the PWM device. For the non-DT case,
- * set the period from platform data if it has not already been set
- * via the PWM lookup table.
- */
- pwm_get_args(pb->pwm, &pargs);
- pb->period = pargs.period;
- if (!pb->period && (data->pwm_period_ns > 0))
- pb->period = data->pwm_period_ns;
-
- pb->lth_brightness = data->lth_brightness * (pb->period / pb->scale);
+ pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW;
--
2.18.0
Powered by blists - more mailing lists