Thanks Scott and Ray for the inputs. I will implement syscon only register access and send out the changes in patch set - v4. Regards, Raveendra On Tue, Feb 23, 2016 at 1:18 AM, Ray Jui <ray.jui@xxxxxxxxxxxx> wrote: > > > On 2/22/2016 11:41 AM, Scott Branden wrote: >> >> My comments below >> >> On 16-02-22 11:36 AM, Dmitry Torokhov wrote: >>> >>> On Fri, Feb 19, 2016 at 11:43:50AM +0530, Raveendra Padasalagi wrote: >>>> >>>> On Thu, Feb 18, 2016 at 8:06 PM, Rob Herring <robh@xxxxxxxxxx> wrote: >>>>> >>>>> On Wed, Feb 17, 2016 at 03:13:44PM +0530, Raveendra Padasalagi wrote: >>>>>> >>>>>> In Cygnus SOC touch screen controller registers are shared >>>>>> with ADC and flex timer. Using readl/writel could lead to >>>>>> race condition. So touch screen driver is enhanced to support >>>>>> >>>>>> 1. If touchscreen register's are not shared. Register access >>>>>> is handled through readl/writel if "brcm,iproc-touchscreen" >>>>>> compatible is provided in touchscreen dt node. This will help >>>>>> for future SOC's if comes with dedicated touchscreen IP register's. >>>>>> >>>>>> 2. If touchscreen register's are shared with other IP's, register >>>>>> access is handled through syscon framework API's to take care of >>>>>> mutually exclusive access. This feature can be enabled by selecting >>>>>> "brcm,iproc-touchscreen-syscon" compatible string in the touchscreen >>>>>> dt node. >>>>>> >>>>>> Hence touchscreen dt node bindings document is updated to take care >>>>>> of above changes in the touchscreen driver. >>>>>> >>>>>> Signed-off-by: Raveendra Padasalagi >>>>>> <raveendra.padasalagi@xxxxxxxxxxxx> >>>>>> Reviewed-by: Ray Jui <ray.jui@xxxxxxxxxxxx> >>>>>> Reviewed-by: Scott Branden <scott.branden@xxxxxxxxxxxx> >>>>>> --- >>>>>> .../input/touchscreen/brcm,iproc-touchscreen.txt | 57 >>>>>> +++++++++++++++++++--- >>>>>> 1 file changed, 51 insertions(+), 6 deletions(-) >>>>>> >>>>>> diff --git >>>>>> >>>>>> a/Documentation/devicetree/bindings/input/touchscreen/brcm,iproc-touchscreen.txt >>>>>> >>>>>> b/Documentation/devicetree/bindings/input/touchscreen/brcm,iproc-touchscreen.txt >>>>>> >>>>>> index 34e3382..f530c25 100644 >>>>>> --- >>>>>> >>>>>> a/Documentation/devicetree/bindings/input/touchscreen/brcm,iproc-touchscreen.txt >>>>>> >>>>>> +++ >>>>>> >>>>>> b/Documentation/devicetree/bindings/input/touchscreen/brcm,iproc-touchscreen.txt >>>>>> >>>>>> @@ -1,12 +1,30 @@ >>>>>> * Broadcom's IPROC Touchscreen Controller >>>>>> >>>>>> Required properties: >>>>>> -- compatible: must be "brcm,iproc-touchscreen" >>>>>> -- reg: physical base address of the controller and length of >>>>>> memory mapped >>>>>> - region. >>>>>> +- compatible: should be one of >>>>>> + "brcm,iproc-touchscreen" >>>>>> + "brcm,iproc-touchscreen-syscon" >>>>> >>>>> >>>>> More specific and this is not how you do syscon. Either the block is or >>>>> isn't. You can't have it both ways. >>>> >>>> >>>> Existing driver has support for reg, if we modify now to support only >>>> syscon >>>> then this driver will not work if some one wishes to use previous >>>> kernel version's >>>> dt and vice versa. Basically this breaks dt compatibility. Is that ok ? >>> >>> >>> But the issue is that the driver does not actually work correctly with >>> direct register access on those systems, since the registers are >>> actually shared with other components. I am not quite sure if it is OK >>> to break DT binding in this case... >> >> >> The driver does work correctly with direct register access on those >> systems because the other components using those registers are not >> active in those systems - so syscon is not needed in those cases. >> >> I'm ok with not containing backwards compatibility though and always >> using syscon. There are no deployed systems using older versions of the >> upstreamed kernel. >>> >>> >>> Thanks. >>> >> >> Regards, >> Scott > > > The iproc touchscreen is currently activated in the "bcm9hmidc.dtsi" that > represents the optional daughter card installed on reference boards > bcm958300k and bcm958305k. While not maintaining backwards compatibility > *might not* be a serious issue, it would be nice if we can at least make > sure the driver change and DT are merged into the same kernel version so > they stay in sync. > > Going forward, if we are only going to support syscon based implementation, > the existing compatible string "brcm,iproc-touchscreen" is preferred over > "brcm,iproc-touchscreen-syscon". > > Thanks, > > Ray -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
