From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen-Yu Tsai Subject: [PATCH v3 10/15] Bluetooth: hci_bcm: Wait for device to come out of reset after power on Date: Mon, 17 Dec 2018 12:04:44 +0800 Message-ID: <20181217040449.31437-11-wens@csie.org> References: <20181217040449.31437-1-wens@csie.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20181217040449.31437-1-wens@csie.org> Sender: linux-kernel-owner@vger.kernel.org To: Marcel Holtmann , Johan Hedberg , Rob Herring , Mark Rutland , Maxime Ripard Cc: Chen-Yu Tsai , Loic Poulain , linux-bluetooth@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Ondrej Jirman List-Id: devicetree@vger.kernel.org The datasheets for BCM20702 and BCM43438 both have power up time sequence graphs, however they are slightly different. Both chips also have an internal power-on-reset, which holds the chip in reset for a short time after the regulators are enabled. For the BCM20702, the time period from when the regulators are enabled, until the chip settles and comes out of sleep state, is 6564 ~ 8171 us. For the BCM43438, the graph only shows the time period from when the regulators are enabled until the chip responds by driving the host's CTS line low, assuming the host has already driven its RTS line low. This is shown to be 6.5 sleep cycles, with the sleep clock at 32.768 kHz. This is around 2 ms. Wait a full 10 ms after the regulators are enabled to account for signal rising times. Tested-by: Ondrej Jirman Signed-off-by: Chen-Yu Tsai --- drivers/bluetooth/hci_bcm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c index f2101038284e..538ce8059bff 100644 --- a/drivers/bluetooth/hci_bcm.c +++ b/drivers/bluetooth/hci_bcm.c @@ -256,6 +256,9 @@ static int bcm_gpio_set_power(struct bcm_device *dev, bool powered) regulator_bulk_disable(BCM_NUM_SUPPLIES, dev->supplies); } + /* wait for device to power on and come out of reset */ + usleep_range(10000, 20000); + dev->res_enabled = powered; return 0; -- 2.20.0