From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Norris Subject: Re: [PATCH 2/2] mfd: cros ec: spi: Simplify delay handling between SPI messages Date: Mon, 13 Nov 2017 13:22:47 -0800 Message-ID: <20171113212247.GB126873@google.com> References: <1510607140-30582-1-git-send-email-jonathanh@nvidia.com> <1510607140-30582-2-git-send-email-jonathanh@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1510607140-30582-2-git-send-email-jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jon Hunter Cc: Lee Jones , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Shawn Nematbakhsh , Benson Leung , Doug Anderson List-Id: linux-tegra@vger.kernel.org On Mon, Nov 13, 2017 at 09:05:40PM +0000, Jon Hunter wrote: > The EC SPI driver prevents SPI transfers being to rapidly by keeping > track of the time the last transfer was issued via the > 'last_transfer_ns' variable. Previously, if the 'last_transfer_ns' > variable was zero, this indicated that no previous transfer had been > sent and that no delay was needed. However, the EC SPI driver has > been updated to always initialise the 'last_transfer_ns' variable > during probe and therefore, it is no longer necessary to test if it > is zero. Remove the code that checks if this variable is zero. > > Signed-off-by: Jon Hunter Reviewed-by: Brian Norris > --- > drivers/mfd/cros_ec_spi.c | 25 +++++++++---------------- > 1 file changed, 9 insertions(+), 16 deletions(-) > > diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c > index a14196e95e9b..7849d781c6bb 100644 > --- a/drivers/mfd/cros_ec_spi.c > +++ b/drivers/mfd/cros_ec_spi.c > @@ -72,8 +72,7 @@ > * struct cros_ec_spi - information about a SPI-connected EC > * > * @spi: SPI device we are connected to > - * @last_transfer_ns: time that we last finished a transfer, or 0 if there > - * if no record > + * @last_transfer_ns: time that we last finished a transfer. > * @start_of_msg_delay: used to set the delay_usecs on the spi_transfer that > * is sent when we want to turn on CS at the start of a transaction. > * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that > @@ -378,18 +377,15 @@ static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev, > u8 *rx_buf; > u8 sum; > int ret = 0, final_ret; > + unsigned long delay; > > len = cros_ec_prepare_tx(ec_dev, ec_msg); > dev_dbg(ec_dev->dev, "prepared, len=%d\n", len); > > /* If it's too soon to do another transaction, wait */ > - if (ec_spi->last_transfer_ns) { > - unsigned long delay; /* The delay completed so far */ > - > - delay = ktime_get_ns() - ec_spi->last_transfer_ns; > - if (delay < EC_SPI_RECOVERY_TIME_NS) > - ndelay(EC_SPI_RECOVERY_TIME_NS - delay); > - } > + delay = ktime_get_ns() - ec_spi->last_transfer_ns; > + if (delay < EC_SPI_RECOVERY_TIME_NS) > + ndelay(EC_SPI_RECOVERY_TIME_NS - delay); > > rx_buf = kzalloc(len, GFP_KERNEL); > if (!rx_buf) > @@ -510,18 +506,15 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev, > u8 *rx_buf; > int sum; > int ret = 0, final_ret; > + unsigned long delay; > > len = cros_ec_prepare_tx(ec_dev, ec_msg); > dev_dbg(ec_dev->dev, "prepared, len=%d\n", len); > > /* If it's too soon to do another transaction, wait */ > - if (ec_spi->last_transfer_ns) { > - unsigned long delay; /* The delay completed so far */ > - > - delay = ktime_get_ns() - ec_spi->last_transfer_ns; > - if (delay < EC_SPI_RECOVERY_TIME_NS) > - ndelay(EC_SPI_RECOVERY_TIME_NS - delay); > - } > + delay = ktime_get_ns() - ec_spi->last_transfer_ns; > + if (delay < EC_SPI_RECOVERY_TIME_NS) > + ndelay(EC_SPI_RECOVERY_TIME_NS - delay); > > rx_buf = kzalloc(len, GFP_KERNEL); > if (!rx_buf) > -- > 2.7.4 >