Hi Geert,
On Thursday, January 12, 2017, Geert Uytterhoeven wrote:
> This is strange. There are two SDHI channels, but the STBCR12
> documentation (all versions up to rev. 3.00) says the register has MSTP
> bits for four SD host interfaces?
>
> Can you please enlighten me? Thanks!
If you look in the rev 3.00 manual for RZ/A1H, in section
"50.3.2 Card Detect/Write Protect", it says:
* Power-Down mode at Card removal
SD Host Interface module is halted by the MSTP123 bit to MSTP120 bit in
Standby Control Register 12
(STBCR12). If these bits of each channel in STBCR12 are set to 10, low power
consumption is achieved at Card
removal. See section 55, Power-Down Modes
So, there are 2 clock sources for each SDHI channel, and the setting
Options are:
SD Host Interface 0 Module Stop
00: SD Host Interface 0 Module runs.
01: Setting prohibited.
10: Only card detect block in SD Host Interface 0 Module runs.
11: Clock supply to SD Host Interface 0 Module is halted
Previously I've been running with '00' because I was turning EVERYTHING on
in u-boot.
Yesterday, I tested with just '10' and things seem to work OK
for me.
Since the sh_mobile_sdhi/tmio driver only allows for 1 clock per channel,
'10' is my only choice for the DT.
However, looking at a previous BSP for RZ/A1, the driver
arch/arm/mach-shmobile/clock-r7s72100.c had this:
static struct clk mstp_clks[MSTP_NR] = {
[MSTP123] = SH_CLK_MSTP8(&peripheral1_clk, STBCR12, 3, 0), /* SDHI00 */
[MSTP122] = SH_CLK_MSTP8(&peripheral1_clk, STBCR12, 2,
CLK_ENABLE_ON_INIT), /* SDHI01 */
[MSTP121] = SH_CLK_MSTP8(&peripheral1_clk, STBCR12, 1, 0), /* SDHI10 */
[MSTP120] = SH_CLK_MSTP8(&peripheral1_clk, STBCR12, 0,
CLK_ENABLE_ON_INIT), /* SDHI11 */
But...that would make me think on boot it would be set to '01' (setting
prohibited).
I'm going to try and find if "setting prohibited" really just means:
"you can set it this way...but nothing is really going to work unless you
enable the other clock".
If that is the case, is there a DT equivalent to "CLK_ENABLE_ON_INIT" that
I can do for MSTP120(SDHI11) and MSTP120(SDHI01) so they are both cleared
on boot???
Thanks,
Chris
