From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: Re: [PATCH v7 8/8] mfd: cros_ec: spi: Add delay for asserting CS Date: Mon, 15 Jun 2015 13:25:18 +0100 Message-ID: <20150615122518.GH3266@x1> References: <1433847889-7220-1-git-send-email-javier.martinez@collabora.co.uk> <1433847889-7220-9-git-send-email-javier.martinez@collabora.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <1433847889-7220-9-git-send-email-javier.martinez@collabora.co.uk> Sender: linux-kernel-owner@vger.kernel.org To: Javier Martinez Canillas Cc: Samuel Ortiz , Olof Johansson , Doug Anderson , Bill Richardson , Simon Glass , Gwendal Grignou , Stephen Barber , Filipe Brandenburger , Todd Broch , Alexandru M Stan , Heiko Stuebner , linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Chris Zhong List-Id: devicetree@vger.kernel.org On Tue, 09 Jun 2015, Javier Martinez Canillas wrote: > From: Alexandru M Stan >=20 > Some ECs need a little time for waking up before they can accept > SPI data at a high speed. This is configurable via a DT property > "google,cros-ec-spi-pre-delay". >=20 > This patch makes the cros_ec_spi driver to cause a delay before > the beginning of a SPI transaction, to make sure that the EC has > already woken up, if the property has been defined in the DTS. >=20 > Signed-off-by: Alexandru M Stan > Reviewed-by: Doug Anderson > Signed-off-by: Chris Zhong > Signed-off-by: Javier Martinez Canillas > Tested-by: Heiko Stuebner > Acked-by: Lee Jones > Acked-by: Olof Johansson Applied, thanks. > --- >=20 > Changes since v6: > - Add Olof Johansson Acked-by tag >=20 > Changes since v5: None. >=20 > Changes since v4: None. >=20 > Changes since v3: > - New patch, split DT binding and driver implementation as suggested > by Lee Jones. > - Add tested-by tag from Heiko Stuebner. > - Add acked-by tag from Lee Jones. > --- > drivers/mfd/cros_ec_spi.c | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) >=20 > diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c > index faba03e2f1ef..16f228dc243f 100644 > --- a/drivers/mfd/cros_ec_spi.c > +++ b/drivers/mfd/cros_ec_spi.c > @@ -71,12 +71,15 @@ > * @spi: SPI device we are connected to > * @last_transfer_ns: time that we last finished a transfer, or 0 if= there > * if no record > + * @start_of_msg_delay: used to set the delay_usecs on the spi_trans= fer that > + * is sent when we want to turn on CS at the start of a transac= tion. > * @end_of_msg_delay: used to set the delay_usecs on the spi_transfe= r that > * is sent when we want to turn off CS at the end of a transact= ion. > */ > struct cros_ec_spi { > struct spi_device *spi; > s64 last_transfer_ns; > + unsigned int start_of_msg_delay; > unsigned int end_of_msg_delay; > }; > =20 > @@ -366,7 +369,7 @@ static int cros_ec_pkt_xfer_spi(struct cros_ec_de= vice *ec_dev, > struct ec_host_request *request; > struct ec_host_response *response; > struct cros_ec_spi *ec_spi =3D ec_dev->priv; > - struct spi_transfer trans; > + struct spi_transfer trans, trans_delay; > struct spi_message msg; > int i, len; > u8 *ptr; > @@ -393,13 +396,23 @@ static int cros_ec_pkt_xfer_spi(struct cros_ec_= device *ec_dev, > goto exit; > } > =20 > + /* > + * Leave a gap between CS assertion and clocking of data to allow t= he > + * EC time to wakeup. > + */ > + spi_message_init(&msg); > + if (ec_spi->start_of_msg_delay) { > + memset(&trans_delay, 0, sizeof(trans_delay)); > + trans_delay.delay_usecs =3D ec_spi->start_of_msg_delay; > + spi_message_add_tail(&trans_delay, &msg); > + } > + > /* Transmit phase - send our message */ > memset(&trans, 0, sizeof(trans)); > trans.tx_buf =3D ec_dev->dout; > trans.rx_buf =3D rx_buf; > trans.len =3D len; > trans.cs_change =3D 1; > - spi_message_init(&msg); > spi_message_add_tail(&trans, &msg); > ret =3D spi_sync(ec_spi->spi, &msg); > =20 > @@ -602,6 +615,10 @@ static void cros_ec_spi_dt_probe(struct cros_ec_= spi *ec_spi, struct device *dev) > u32 val; > int ret; > =20 > + ret =3D of_property_read_u32(np, "google,cros-ec-spi-pre-delay", &v= al); > + if (!ret) > + ec_spi->start_of_msg_delay =3D val; > + > ret =3D of_property_read_u32(np, "google,cros-ec-spi-msg-delay", &v= al); > if (!ret) > ec_spi->end_of_msg_delay =3D val; --=20 Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org =E2=94=82 Open source software for ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog