mfd: madera: Don't use regmap_read_poll_timeout to poll for BOOT_DONE

While polling for BOOT_DONE the chip could NAK a read because it is
still booting, which would terminate the regmap_read_poll_timeout()
with an error.

Instead implement a polling loop that ignores read errors so we
always poll until the chip signals boot or the loop times out.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/drivers/mfd/madera-core.c b/drivers/mfd/madera-core.c
index 8cfea969b060277dd53633a114b534e3eefdb2e0..440030cecbbdae952d2a64f1050473b2f254337d 100644 (file)
--- a/drivers/mfd/madera-core.c
+++ b/drivers/mfd/madera-core.c
@@ -132,32 +132,39 @@ const char *madera_name_from_type(enum madera_type type)
 }
 EXPORT_SYMBOL_GPL(madera_name_from_type);
 
-#define MADERA_BOOT_POLL_MAX_INTERVAL_US  5000
-#define MADERA_BOOT_POLL_TIMEOUT_US     25000
+#define MADERA_BOOT_POLL_INTERVAL_USEC         5000
+#define MADERA_BOOT_POLL_TIMEOUT_USEC          25000
 
 static int madera_wait_for_boot(struct madera *madera)
 {
+       ktime_t timeout;
        unsigned int val;
-       int ret;
+       int ret = 0;
 
        /*
         * We can't use an interrupt as we need to runtime resume to do so,
         * so we poll the status bit. This won't race with the interrupt
         * handler because it will be blocked on runtime resume.
+        * The chip could NAK a read request while it is booting so ignore
+        * errors from regmap_read.
         */
-       ret = regmap_read_poll_timeout(madera->regmap,
-                                      MADERA_IRQ1_RAW_STATUS_1,
-                                      val,
-                                      (val & MADERA_BOOT_DONE_STS1),
-                                      MADERA_BOOT_POLL_MAX_INTERVAL_US,
-                                      MADERA_BOOT_POLL_TIMEOUT_US);
-
-       if (ret)
-               dev_err(madera->dev, "Polling BOOT_DONE_STS failed: %d\n", ret);
+       timeout = ktime_add_us(ktime_get(), MADERA_BOOT_POLL_TIMEOUT_USEC);
+       regmap_read(madera->regmap, MADERA_IRQ1_RAW_STATUS_1, &val);
+       while (!(val & MADERA_BOOT_DONE_STS1) &&
+              !ktime_after(ktime_get(), timeout)) {
+               usleep_range(MADERA_BOOT_POLL_INTERVAL_USEC / 2,
+                            MADERA_BOOT_POLL_INTERVAL_USEC);
+               regmap_read(madera->regmap, MADERA_IRQ1_RAW_STATUS_1, &val);
+       };
+
+       if (!(val & MADERA_BOOT_DONE_STS1)) {
+               dev_err(madera->dev, "Polling BOOT_DONE_STS timed out\n");
+               ret = -ETIMEDOUT;
+       }
 
        /*
         * BOOT_DONE defaults to unmasked on boot so we must ack it.
-        * Do this unconditionally to avoid interrupt storms.
+        * Do this even after a timeout to avoid interrupt storms.
         */
        regmap_write(madera->regmap, MADERA_IRQ1_STATUS_1,
                     MADERA_BOOT_DONE_EINT1);