Thread (14 messages) 14 messages, 3 authors, 2013-12-27

[PATCH 2/3] mmc: dw_mmc: add dw_mmc-k3 for k3 platform

From: Seungwon Jeon <hidden>
Date: 2013-12-16 07:29:38
Also in: linux-devicetree, linux-mmc

On Mon, December 16, 2013, Zhangfei Gao wrote: 
Dear Seungwon

On 12/16/2013 11:50 AM, Seungwon Jeon wrote:
quoted
On Sat, December 14, 2013, Zhangfei Gao wrote:
quoted
quoted
+	/* SoC portion */
+	dwmmc_0: dwmmc0 at fcd03000 {
+		compatible = "hisilicon,hi4511-dw-mshc";
+		reg = <0xfcd03000 0x1000>;
+		interrupts = <0 16 4>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		clocks = <&mmc_clock HI3620_SD_CIUCLK>, <&clock HI3620_DDRC_PER_CLK>;
+		clock-names = "ciu", "biu";
+		clock-freq-table =
+		<25000000 0 50000000 25000000 50000000 100000000 0 50000000>;
I think it could be solved with mmc->f_min and mmc->f_max(from clock-freq-min-max property)
if there is no limitation per each speed mode. As seeing described table, it looks that.
Have tried them before, but unfortunately, they are different.

The controller can not generate clock itself, while depending on the
outside clock generator, which may require to change clock source in
differnt mode.

The value we want is set the capacibility of the clock input and the max
clock freq where mmc works stable in that mode, which may be different
in different mode.

clock-freq-min-max will set the value for set_ios.
For example, we use 25M as clock capability when init, which can not be
set as freq-min, and used as set_ios, where 400K should be used,
otherwise init definitely fail.
Can you check 'f_init' within 'drivers/mmc/core/core.c' file?
If you set 'f_min = 25000000' for init-sequence, mmc_set_ios() will pass that rate through 'ios.clock'
Then, dw_mmc-k3 can do clk_set_rate() with 25MHz at dw_mci_k3_set_ios().
And other required speeds for each mode seem not specific compared with standard spec.
Also clk_set_rate() would be possible with 'ios.clock' instead of specific table.
I just referred your example's clock-freq-table above.
quoted
quoted
+static int dw_mci_k3_suspend(struct device *dev)
+{
+	struct dw_mci *host = dev_get_drvdata(dev);
+
+	if (!IS_ERR(host->ciu_clk))
+		clk_disable_unprepare(host->ciu_clk);
+
+	return dw_mci_suspend(host);
If k3 needs clk_disable here, dw_mci_suspend()is expected to be called prior to
clk_disable_unprepare()?
quoted
Of course, it's ok at present though.
Sure, it can be switched, though dw_mci_suspend does nothing related
with clock now.
Yes, but if some works with ciu_clk is added in dw_mci_suspend(), it will affect.

Thanks,
Seungwon Jeon
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help