From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: Re: [PATCH v3 3/7] mfd: cros_ec: spi: Make the cros_ec_spi timeout more reliable Date: Tue, 20 May 2014 09:45:03 +0100 Message-ID: <20140520084503.GD24991@lee--X1> References: <1398879850-9111-1-git-send-email-dianders@chromium.org> <1398879850-9111-4-git-send-email-dianders@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <1398879850-9111-4-git-send-email-dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Doug Anderson Cc: swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org, abrestic-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, dgreid-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org, sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sameo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On Wed, 30 Apr 2014, Doug Anderson wrote: > The cros_ec_spi transfer had two problems with its timeout code: >=20 > 1. It looked at the timeout even in the case that it found valid data= =2E > 2. If the cros_ec_spi code got switched out for a while, it's possibl= e > it could get a timeout after a single loop. Let's be paranoid and > make sure we do one last transfer after the timeout expires. >=20 > Signed-off-by: Doug Anderson > Acked-by: Lee Jones > Reviewed-by: Simon Glass > Tested-by: Andrew Bresticker > Tested-by: Stephen Warren > --- > Changes in v3: None > Changes in v2: None >=20 > drivers/mfd/cros_ec_spi.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) Applied, thanks. > diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c > index a2a605d..4f863c3 100644 > --- a/drivers/mfd/cros_ec_spi.c > +++ b/drivers/mfd/cros_ec_spi.c > @@ -113,7 +113,9 @@ static int cros_ec_spi_receive_response(struct cr= os_ec_device *ec_dev, > =20 > /* Receive data until we see the header byte */ > deadline =3D jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS); > - do { > + while (true) { > + unsigned long start_jiffies =3D jiffies; > + > memset(&trans, 0, sizeof(trans)); > trans.cs_change =3D 1; > trans.rx_buf =3D ptr =3D ec_dev->din; > @@ -134,12 +136,19 @@ static int cros_ec_spi_receive_response(struct = cros_ec_device *ec_dev, > break; > } > } > + if (ptr !=3D end) > + break; > =20 > - if (time_after(jiffies, deadline)) { > + /* > + * Use the time at the start of the loop as a timeout. This > + * gives us one last shot at getting the transfer and is useful > + * in case we got context switched out for a while. > + */ > + if (time_after(start_jiffies, deadline)) { > dev_warn(ec_dev->dev, "EC failed to respond in time\n"); > return -ETIMEDOUT; > } > - } while (ptr =3D=3D end); > + } > =20 > /* > * ptr now points to the header byte. Copy any valid data to the --=20 Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org =E2=94=82 Open source software for ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog