On 03/30/2016 08:46 AM, Shawn Lin wrote:
在 2016/3/29 16:23, zhangfei 写道:
More to think, Is it ok to match the behaviour of bootloader stage?
My bootloader doesn't assert the reset pin of dw_mmc, so it seams if
I want to fix you issue on kernel stage, I need a new round of
assert->delay->deassert.
The process like delay (if required) should be abstracted in reset
driver.
reset framework just export reset_control_assert/reset_control_deassert
API.
Unfortunately not find clear description in Documentation/.
Suppose deassert is like start, while assert is like stop.
yes, no docs except dt-bindings..... So seems the usage of these two
APIs depends on the implementation of reset controller driver
drivers/reset/core.c
reset_control_deassert - deasserts the reset line
reset_control_assert - asserts the reset line
More example:
drivers/mmc/host/sdhci-st.c
drivers/mmc/host/sunxi-mmc.c
drivers/usb/host/ohci-platform.c
drivers/i2c/busses/i2c-mv64xxx.c
But I'm afraid I have to nack here....
Looking at these files:
drivers/dma/stm32-dma.c
drivers/net/ethernet/mediatek/mtk_eth_soc.c
drivers/devfreq/tegra-devfreq.c
drivers/crypto/rockchip/rk3288_crypto.c
drivers/thermal/rockchip_thermal.c
drivers/thermal/tegra_soctherm.c
drivers/i2c/busses/i2c-tegra.c
....
they just do the way like: assert->[delay](maybe abstracted)->deassert
I think these drivers are vendor specific, so they can do
the reset operations in consistent with the implementation of
their platforms' reset controller drivers.
Yes, have checked drivers/i2c/busses/i2c-tegra.c
reset_control_assert(i2c_dev->rst);
udelay(2);
reset_control_deassert(i2c_dev->rst);
This usage looks strange, reset does not mean gpio reset, it maybe
register accessing.
I think all these three operation should be abstracted to deassert
function, while cover the details for sharing.
However, not doc describing the assert/deassert behavior so causing
confusion.
But, dw_mmc is shared by many Socs. So It's not good to do it in
dw_mci_probe, otherwise you force my reset controller driver to be
implemented in the same way as yours..... Right?
How about move it to your drv_data->init callback?
Yes, we can.
But firstly we should consider put in common file for sharing, otherwise
there maybe many assert/deassert in dw_mmc-xx.c.
Guodong may send another version and wait for Jaehoon's decision.
Thanks
--
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
