Hello JJ, On 15/06/2014 10:53, Jean-Jacques Hiblot wrote: > On 06/09/2014 06:04 PM, Boris BREZILLON wrote: >> The HLCDC IP available on some Atmel SoCs (i.e. at91sam9n12, at91sam9x5 >> family or sama5d3 family) exposes 2 subdevices: >> - a display controller (controlled by a DRM driver) >> - a PWM chip >> >> Add support for the MFD device which will just retrieve HLCDC clocks and >> create a regmap so that subdevices can access the HLCDC register range >> concurrently. >> >> Signed-off-by: Boris BREZILLON <boris.brezillon@xxxxxxxxxxxxxxxxxx> >> --- >> .../devicetree/bindings/mfd/atmel-hlcdc.txt | 41 ++++++++ >> drivers/mfd/Kconfig | 11 ++ >> drivers/mfd/Makefile | 1 + [...] >> + memset(&config, 0, sizeof(config)); >> + config.reg_bits = 32; >> + config.val_bits = 32; >> + config.reg_stride = 4; >> + config.max_register = (resource_size(res) / 4) - 1; >> + hlcdc->regmap = devm_regmap_init_mmio_clk(dev, "periph_clk", regs, >> + &config); > I don't think it's necessary to use "periph_clk" here. This clock will > always be running because the HLCDC needs it to work (it's not just an > interface clock). In the end it's just some extra work for each register > access. Yes, I thought about removing this clk from regmap registration too (for the exact same reason: avoiding extra enable/disable work when accessing registers), but ATM I do not prepare/enable periph_clk in the hlcdc-pwm driver, this means the regmap won't work until the hlcdc-dc driver has probed the display controller device. How about preparing/enabling the periph_clk in the MFD device, so that PWM and Display Controller subdevices won't have to bother about this clk, and the regmap will work as expected ? Or, should we just prepare/enable the periph clock in each subdevices ? Best Regards, Boris -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
