In rpi-firmware 25e2b597ebfb2495eab4816a276758dcc6ea21f1, the GET_CLOCK_RATE mailbox property was changed to return the last value set by SET_CLOCK_RATE.
https://github.com/raspberrypi/firmware/issues/1619#issuecomment-917025502 Due to this change in firmware behavior, bcm2835_get_mmc_clock now returns a clock rate of zero since we do not issue SET_CLOCK_RATE. This results in degraded MMC performance. SET_CLOCK_RATE fixes the clock to a specific value and disables scaling so is not an ideal solution. Instead, fallback to GET_MAX_CLOCK_RATE in bcm2835_get_mmc_clock if GET_CLOCK_RATE returns zero. Signed-off-by: Vincent Fazio <vfa...@xes-inc.com> --- arch/arm/mach-bcm283x/include/mach/mbox.h | 2 ++ arch/arm/mach-bcm283x/msg.c | 19 ++++++++++++++++++- 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/arch/arm/mach-bcm283x/include/mach/mbox.h b/arch/arm/mach-bcm283x/include/mach/mbox.h index 2ae2d3d97c..7dcac583cc 100644 --- a/arch/arm/mach-bcm283x/include/mach/mbox.h +++ b/arch/arm/mach-bcm283x/include/mach/mbox.h @@ -224,6 +224,8 @@ struct bcm2835_mbox_tag_set_power_state { }; #define BCM2835_MBOX_TAG_GET_CLOCK_RATE 0x00030002 +#define BCM2835_MBOX_TAG_GET_MAX_CLOCK_RATE 0x00030004 +#define BCM2835_MBOX_TAG_GET_MIN_CLOCK_RATE 0x00030007 #define BCM2835_MBOX_CLOCK_ID_EMMC 1 #define BCM2835_MBOX_CLOCK_ID_UART 2 diff --git a/arch/arm/mach-bcm283x/msg.c b/arch/arm/mach-bcm283x/msg.c index 347aece3cd..ae85e9159e 100644 --- a/arch/arm/mach-bcm283x/msg.c +++ b/arch/arm/mach-bcm283x/msg.c @@ -75,6 +75,7 @@ int bcm2835_get_mmc_clock(u32 clock_id) { ALLOC_CACHE_ALIGN_BUFFER(struct msg_get_clock_rate, msg_clk, 1); int ret; + u32 clock_rate = 0; ret = bcm2835_power_on_module(BCM2835_MBOX_POWER_DEVID_SDHCI); if (ret) @@ -90,7 +91,23 @@ int bcm2835_get_mmc_clock(u32 clock_id) return -EIO; } - return msg_clk->get_clock_rate.body.resp.rate_hz; + clock_rate = msg_clk->get_clock_rate.body.resp.rate_hz; + + if (clock_rate == 0) { + BCM2835_MBOX_INIT_HDR(msg_clk); + BCM2835_MBOX_INIT_TAG(&msg_clk->get_clock_rate, GET_MAX_CLOCK_RATE); + msg_clk->get_clock_rate.body.req.clock_id = clock_id; + + ret = bcm2835_mbox_call_prop(BCM2835_MBOX_PROP_CHAN, &msg_clk->hdr); + if (ret) { + printf("bcm2835: Could not query max eMMC clock rate\n"); + return -EIO; + } + + clock_rate = msg_clk->get_clock_rate.body.resp.rate_hz; + } + + return clock_rate; } int bcm2835_get_video_size(int *widthp, int *heightp) -- 2.25.1
