Re: [PATCH RFC v2 2/2] simplefb: Claim and enable regulators
From: Hans de Goede
Date: Wed Oct 21 2015 - 04:11:50 EST
Hi,
On 21-10-15 10:04, Chen-Yu Tsai wrote:
Hi,
On Wed, Oct 21, 2015 at 3:54 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
Hi,
On 21-10-15 07:59, Chen-Yu Tsai wrote:
This claims and enables regulators listed in the simple framebuffer dt
node. This is needed so that regulators powering the display pipeline
and external hardware, described in the device node and known by the
kernel code, will remain properly enabled.
Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
---
drivers/video/fbdev/simplefb.c | 122
++++++++++++++++++++++++++++++++++++++++-
1 file changed, 121 insertions(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/simplefb.c
b/drivers/video/fbdev/simplefb.c
index 52c5c7e63b52..c4ee10d83a70 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -28,7 +28,10 @@
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
+#include <linux/of.h>
#include <linux/of_platform.h>
+#include <linux/parser.h>
+#include <linux/regulator/consumer.h>
static struct fb_fix_screeninfo simplefb_fix = {
.id = "simple",
@@ -174,6 +177,10 @@ struct simplefb_par {
int clk_count;
struct clk **clks;
#endif
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+ u32 regulator_count;
+ struct regulator **regulators;
+#endif
};
#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
@@ -269,6 +276,112 @@ static int simplefb_clocks_init(struct simplefb_par
*par,
static void simplefb_clocks_destroy(struct simplefb_par *par) { }
#endif
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+
+#define SUPPLY_SUFFIX "-supply"
+
+/*
+ * Regulator handling code.
+ *
+ * Here we handle the num-supplies and vin*-supply properties of our
+ * "simple-framebuffer" dt node. This is necessary so that we can make
sure
+ * that any regulators needed by the display hardware that the bootloader
+ * set up for us (and for which it provided a simplefb dt node), stay up,
+ * for the life of the simplefb driver.
+ *
+ * When the driver unloads, we cleanly disable, and then release the
+ * regulators.
+ *
+ * We only complain about errors here, no action is taken as the most
likely
+ * error can only happen due to a mismatch between the bootloader which
set
+ * up simplefb, and the regulator definitions in the device tree. Chances
are
+ * that there are no adverse effects, and if there are, a clean teardown
of
+ * the fb probe will not help us much either. So just complain and carry
on,
+ * and hope that the user actually gets a working fb at the end of
things.
+ */
+static int simplefb_regulators_init(struct simplefb_par *par,
+ struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct property *prop;
+ struct regulator *regulator;
+ const char *p;
+ int count = 0, i = 0, ret;
+
+ if (dev_get_platdata(&pdev->dev) || !np)
+ return 0;
+
+ /* Count the number of regulator supplies */
+ for_each_property_of_node(np, prop) {
+ p = strstr(prop->name, SUPPLY_SUFFIX);
+ if (p && p != prop->name)
+ count++;
+ }
+
+ if (!count)
+ return 0;
+
+ par->regulators = devm_kcalloc(&pdev->dev, count,
+ sizeof(struct regulator *),
GFP_KERNEL);
+ if (!par->regulators)
+ return -ENOMEM;
+
+ /* Get all the regulators */
+ for_each_property_of_node(np, prop) {
+ char name[32]; /* 32 is max size of property name */
+
+ p = strstr(prop->name, SUPPLY_SUFFIX);
+ if (p && p != prop->name)
+ continue;
+
+ strlcpy(name, prop->name,
+ strlen(prop->name) - sizeof(SUPPLY_SUFFIX) + 1);
+ regulator = devm_regulator_get_optional(&pdev->dev, name);
+ if (IS_ERR(regulator)) {
+ if (PTR_ERR(regulator) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+ dev_err(&pdev->dev, "regulator %s not found:
%ld\n",
+ name, PTR_ERR(regulator));
+ continue;
+ }
+ par->regulators[i++] = regulator;
So you only fill slots when the regulator_get has succeeded
+ }
+ par->regulator_count = i;
and regulator_count now is the amount of successfully gotten regulators
(which may be different from count).
+
+ /* Enable all the regulators */
+ for (i = 0; i < par->regulator_count; i++) {
+ if (par->regulators[i]) {
That means that this "if" is not necessary, it will always be true.
Right. This is leftover code from the first version. I'll remove it.
+ ret = regulator_enable(par->regulators[i]);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "failed to enable regulator %d:
%d\n",
+ i, ret);
+ devm_regulator_put(par->regulators[i]);
+ par->regulators[i] = NULL;
Note here.
+ }
+ }
+ }
+
+ return 0;
+}
+
+static void simplefb_regulators_destroy(struct simplefb_par *par)
+{
+ int i;
+
+ if (!par->regulators)
+ return;
+
+ for (i = 0; i < par->regulator_count; i++)
+ if (par->regulators[i])
And idem for this if.
This is still needed, since if we fail to enable any regulator, we just
ignore it, call regulator_put() on it, and forget about it (set the entry
to NULL). See the noted place above.
Ah right, ok lets keep that in then :)
Regards,
Hans
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