From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH] i2c: designware: deduce speed mode from device tree setting Date: Wed, 20 Aug 2014 10:22:57 +0100 Message-ID: <20140820092257.GA21174@leverpostej> References: <1408479529-24249-1-git-send-email-atull@opensource.altera.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1408479529-24249-1-git-send-email-atull-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "atull-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org" Cc: "wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org" , "baruch-NswTu9S1W3P6gbPvEgmw2w@public.gmane.org" , "mika.westerberg-VuQAYsv1563Yd54FQh9/CA@public.gmane.org" , "grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "skuribay-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org" , "Romain.Baeriswyl-ux6zf3SgZrrQT0dZR+AlfA@public.gmane.org" , "rafael.j.wysocki-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org" , "alan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org" , "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "delicious.quinoa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "dinguyen-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org" , "yvanderv-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org" List-Id: devicetree@vger.kernel.org On Tue, Aug 19, 2014 at 09:18:49PM +0100, atull-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org wrote: > From: Alan Tull > > Use the documented, but unimplemented "clock-frequency" > Device Tree setting as a guide on whether to set the speed > mode bits in DW_IC_CON to standard or fast i2c mode. > > Previously, the driver was hardwired to fast mode. Default > to fast mode if the "clock-frequency" property is not present > for backwards compatiblity. > > Signed-off-by: Alan Tull > --- > drivers/i2c/busses/i2c-designware-platdrv.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c > index bc87733..18cd3d9 100644 > --- a/drivers/i2c/busses/i2c-designware-platdrv.c > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c > @@ -122,7 +122,8 @@ static int dw_i2c_probe(struct platform_device *pdev) > struct dw_i2c_dev *dev; > struct i2c_adapter *adap; > struct resource *mem; > - int irq, r; > + int irq, r, ret, speed = DW_IC_CON_SPEED_FAST; > + u32 bus_rate; > > irq = platform_get_irq(pdev, 0); > if (irq < 0) { > @@ -167,6 +168,11 @@ static int dw_i2c_probe(struct platform_device *pdev) > of_property_read_u32(pdev->dev.of_node, > "i2c-scl-falling-time-ns", > &dev->scl_falling_time); > + > + ret = of_property_read_u32(pdev->dev.of_node, > + "clock-frequency", &bus_rate); > + if (!ret && (bus_rate <= 100000)) > + speed = DW_IC_CON_SPEED_STD; This looks a bit odd. If the device only supports two particular speeds why do we accept any other speed in the clock-frequency property? Surely we should at least warn that something was off? Thanks, Mark > } > > dev->functionality = > @@ -177,7 +183,7 @@ static int dw_i2c_probe(struct platform_device *pdev) > I2C_FUNC_SMBUS_WORD_DATA | > I2C_FUNC_SMBUS_I2C_BLOCK; > dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE | > - DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST; > + DW_IC_CON_RESTART_EN | speed; > > /* Try first if we can configure the device from ACPI */ > r = dw_i2c_acpi_configure(pdev); > -- > 1.7.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe devicetree" in > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >