Hi Jonas,
On 7/30/26 4:35 PM, Jonas Karlman wrote:
Hi Quentin,
On 7/30/2026 4:17 PM, Quentin Schulz wrote:
Hi Jonas,
On 7/30/26 2:30 PM, Jonas Karlman wrote:
Rockchip SoCs can automatically switch between jtag and sdmmc based on
the following rules:
- all the SDMMC pins including SDMMC_DET set as SDMMC function in GRF,
- force_jtag bit in GRF is 1,
- SDMMC_DET is low (no card detected),
Note that the BootROM may mux all SDMMC pins in their SDMMC function or
not, depending on the boot medium that were tried.
Because SDMMC_DET pin is not guaranteed to be used as an SD card card
detect pin, it could be low at boot or even switch at runtime, which
would enable the jtag function and render the SD card unusable.
Or boards using cd-gpios may switch the SDMMC_DET pin to GPIO function,
which would enable the jtag function and render the SD card unusable.
With commit d0a838bdc629 ("Subtree merge tag 'v7.1-dts' of dts repo [1]
into dts/upstream") there are now RK3576 boards that have changed to use
cd-gpios for the SDMMC_DET pin, e.g. NanoPi R76S, that may have issues
detecting SD card unless force_jtag is disabled.
Signed-off-by: Jonas Karlman <[email protected]>
---
arch/arm/mach-rockchip/rk3576/rk3576.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/arm/mach-rockchip/rk3576/rk3576.c
b/arch/arm/mach-rockchip/rk3576/rk3576.c
index e3e93f663959..0f41f210a9a5 100644
--- a/arch/arm/mach-rockchip/rk3576/rk3576.c
+++ b/arch/arm/mach-rockchip/rk3576/rk3576.c
@@ -26,6 +26,9 @@
#define SYS_SGRF_SOC_CON15 0x005C
#define SYS_SGRF_SOC_CON20 0x0070
+#define TOP_IOC_BASE 0x26044000
+#define IOC_MISC_CON 0x00F0
+
#define FW_PMU1SGRF_BASE 0x26003000
#define PMU1SGRF_SLV_LOOKUP0 0x80
@@ -190,6 +193,10 @@ int arch_cpu_init(void)
*/
writel(0xffffff00, SYS_SGRF_BASE + SYS_SGRF_SOC_CON20);
+ /* Disable JTAG exposed on SDMMC pins (GPIO2A2 and GPIO2A3) */
+ if (IS_ENABLED(CONFIG_ROCKCHIP_DISABLE_FORCE_JTAG))
+ writel(0x00020000, TOP_IOC_BASE + IOC_MISC_CON);
+
Please:
- use a constant (e.g. #define TOP_IOC_FORCE_JTAG BIT(1))
- use rk_clrreg(TOP_IOC_BASE + IOC_MISC_CON, TOP_IOC_FORCE_JTAG)
It'd be nice to be consistent here and do the same for other writel all
over arch/arm/mach-rockchip/ but that's a different kind of task :)
I know we are inconsistent across multiple SoCs, however in rk3576 we
are exclusivity using writel() so I decided to continue to use writel()
for this change for consistency with surrounding code, and therefore
disagree with your suggested changes :-)
In my opinion mixed used of both writel() and rk_reg() funcs are worse
than a consistent use of writel() within same file and function.
I understand but this here is quite misleading as it could be understood
as "you need to write bit 16 to disable JTAG" which is technically
correct, but only because bit 1 is 0 and that is the one that actually
matters.
Can we maybe compromise on using
writel(RK_CLRBITS(TOP_IOC_FORCE_JTAG), TOP_IOC_BASE + IOC_MISC_CON)
?
Cheers,
Quentin
