Re: [PATCH] ARM: dts: socfpga: remove syscon compatible string for sysmgr node

[Dinh Nguyen]

On 2/11/25 06:18, Rabara, Niravkumar L wrote:
> Hi Dinh,
>
> > -----Original Message-----
> > From: Dinh Nguyen <dinguyen@xxxxxxxxxx>
> > Sent: Tuesday, 11 February, 2025 12:15 PM
> > To: Rabara, Niravkumar L <niravkumar.l.rabara@xxxxxxxxx>; Rob Herring
> > <robh@xxxxxxxxxx>; Krzysztof Kozlowski <krzk+dt@xxxxxxxxxx>; Conor Dooley
> > <conor+dt@xxxxxxxxxx>; devicetree@xxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx
> > Cc: lkp <lkp@xxxxxxxxx>
> > Subject: Re: [PATCH] ARM: dts: socfpga: remove syscon compatible string for
> > sysmgr node
> >
> > > Yes, I have tested this using NFS boot, however I didn't observe any
> > > issue with SD/MMC driver.
> > >
> > > => fdt print /soc/mmc@ff808000
> > > mmc@ff808000 {
> > > 	#address-cells = <0x00000001>;
> > > 	#size-cells = <0x00000000>;
> > > 	compatible = "altr,socfpga-dw-mshc";
> > > 	reg = <0xff808000 0x00001000>;
> > > 	interrupts = <0x00000000 0x00000062 0x00000004>;
> > > 	fifo-depth = <0x00000400>;
> > > 	clocks = <0x0000001a 0x00000024>;
> > > 	clock-names = "biu", "ciu";
> > > 	resets = <0x00000006 0x00000027>;
> > > 	altr,sysmgr-syscon = <0x0000001c 0x00000028 0x00000004>;
> > > 	status = "okay";
> > > 	cap-sd-highspeed;
> > > 	cap-mmc-highspeed;
> > > 	broken-cd;
> > > 	bus-width = <0x00000004>;
> > > 	clk-phase-sd-hs = <0x00000000 0x00000087>;
> > > 	phandle = <0x00000029>;
> > > };
> > > => fdt print /soc/sysmgr@ffd06000
> > > sysmgr@ffd06000 {
> > > 	compatible = "altr,sys-mgr";
> > > 	reg = <0xffd06000 0x00000300>;
> > > 	cpu1-start-addr = <0xffd06230>;
> > > 	phandle = <0x0000001c>;
> > > };
> > >
> > > [    1.095784] mmc_host mmc0: Bus speed (slot 0) = 50000000Hz (slot req
> > 50000000Hz, actual 50000000HZ div = 0)
> > > [    1.105692] mmc0: new high speed SDHC card at address 0001
> > > [    1.108238] at24 0-0051: supply vcc not found, using dummy regulator
> > > [    1.111817] mmcblk0: mmc0:0001 SD32G 29.1 GiB
> > > [    1.118872] at24 0-0051: 4096 byte 24c32 EEPROM, writable, 32
> > bytes/write
> > > [    1.129186]  mmcblk0: p1 p2 p3
> > >
> > > .
> > >
> > > root@arria10:~# ls /dev/mmcblk0*
> > > /dev/mmcblk0    /dev/mmcblk0p1  /dev/mmcblk0p2  /dev/mmcblk0p3
> > > root@arria10:~# mount /dev/mmcblk0p1 /tmp/ root@arria10:~# ls /tmp/
> > > extlinux                         socfpga_arria10_socdk_sdmmc.dtb  zImage
> > > fit_spl_fpga.itb                 u-boot.img
> >
> > You didn't really test anything. There's a register in the System Manager that has
> > set the SD/MMC clk-phase in U-Boot. So you won't see the failure unless you
> > explicitly change the value in that register and then boot Linux, then you will see
> > the failure. If you look at drivers/mmc/host/dw_mmc-pltfm.c and look at the
> > function dw_mci_socfpga_priv_init(), you can see that work in action. If you
> > remove the syscon property, then that portion of the driver will fail.
> > Also the ethernet driver is using the system manager's to set the correct PHY
> > mode through syscon. I think you need to test this patch more thoroughly.
> >
> > DInh
>
> Altera System Manager driver (drivers/mfd/altera-sysmgr.c) is enabled
> in "socfpga_defconfig" - i.e. CONFIG_MFD_ALTERA_SYSMGR=y
>
> So, SoCFPGA always using drivers/mfd/altera-sysmgr.c for System Manager
> register access, not the generic "syscon" drivers/mfd/syscon.c.
> That's why we do not need "syscon" compatible for fall back mechanism.
>
> 	sysmgr: sysmgr@ffd08000 {
> -		compatible = "altr,sys-mgr", "syscon";
> +		compatible = "altr,sys-mgr";
>   		reg = <0xffd08000 0x4000>;
>   	};
> 	mmc: mmc@ff808000 {
> 		…
> 		altr,sysmgr-syscon = <&sysmgr 0x28 4>;
> 		clk-phase-sd-hs = <0>, <135>;
> 		…
> 	};
> 	gmac0: ethernet@ff800000 {
> 		…
> 		altr,sysmgr-syscon = <&sysmgr 0x44 0>;
> 		…
> 	};
>
>
> Even the sdmmc driver you mentioned is using "drivers/mfd/altera-sysmgr.c"
> not the generic "syscon" drivers/mfd/syscon.c. Same thing for ethernet driver
> as well.
>
> dw_mci_socfpga_priv_init()  {
> 	...
> 	rc = of_property_read_variable_u32_array(np, "clk-phase-sd-hs", &clk_phase[0], 2, 0);
> 	if (rc < 0)
> 		return 0;
>
> 	sys_mgr_base_addr = altr_sysmgr_regmap_lookup_by_phandle(np, "altr,sysmgr-syscon");
> 	if (IS_ERR(sys_mgr_base_addr)) {
> 		dev_warn(host->dev, "clk-phase-sd-hs was specified, but failed to find altr,sys-mgr regmap!\n");
> 		return 0;
> 	}
>
> 	of_property_read_u32_index(np, "altr,sysmgr-syscon", 1, &reg_offset);
> 	of_property_read_u32_index(np, "altr,sysmgr-syscon", 2, &reg_shift);
> 	...
> }
>
> Please let me know if my understanding is incorrect.

But the altera-sysmgr driver is using syscon as the interface:

config MFD_ALTERA_SYSMGR
        bool "Altera SOCFPGA System Manager"
        depends on ARCH_INTEL_SOCFPGA && OF
        select MFD_SYSCON

Can you look at your bootlog and see if you see this message 
""clk-phase-sd-hs was specified, but failed to find altr,sys-mgr regmap!"?

Dinh