From 71ba043e5c5575f3d86536acade70dab6599489b Mon Sep 17 00:00:00 2001 From: Vincent Fazio Date: Mon, 13 Sep 2021 11:22:30 -0500 Subject: [PATCH] arm: rpi: fallback to max clock rate for MMC clock In rpi-firmware 25e2b597ebfb2495eab4816a276758dcc6ea21f1 and later, 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 U-Boot does not call SET_CLOCK_RATE so bcm2835_get_mmc_clock will return zero and can cause degraded MMC performance. Calling SET_CLOCK_RATE fixes the frequency of the clock to a specific value and disables the firmware's clock scaling so is not an option. Instead, fallback to GET_MAX_CLOCK_RATE in bcm2835_get_mmc_clock if GET_CLOCK_RATE returns zero. Signed-off-by: Vincent Fazio --- arch/arm/mach-bcm283x/include/mach/mbox.h | 2 ++ arch/arm/mach-bcm283x/msg.c | 20 +++++++++++++++++++- 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/arch/arm/mach-bcm283x/include/mach/mbox.h b/arch/arm/mach-bcm283x/include/mach/mbox.h index 2ae2d3d97c3..7dcac583cc4 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 347aece3cd8..e2badfecb09 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 +91,24 @@ 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)