Re: [PATCH 1/2] bus: mbus: fix window size calculation for 4GB windows
From: Gregory CLEMENT <hidden>
Date: 2017-09-19 14:43:22
Hi Jan, On lun., ao?t 28 2017, Jan Luebbe [off-list ref] wrote:
At least the Armada XP SoC supports 4GB on a single DRAM window. Because the size register values contain the actual size - 1, the MSB is set in that case. For example, the SDRAM window's control register's value is 0xffffffe1 for 4GB (bits 31 to 24 contain the size). The MBUS driver reads back each window's size from registers and calculates the actual size as (control_reg | ~DDR_SIZE_MASK) + 1, which overflows for 32 bit values, resulting in other miscalculations further on (a bad RAM window for the CESA crypto engine calculated by mvebu_mbus_setup_cpu_target_nooverlap() in my case). This patch changes the type in 'struct mbus_dram_window' from u32 to u64, which allows us to keep using the same register calculation code in most MBUS-using drivers (which calculate ->size - 1 again).
Your patch looks good, but as it is a fix we should also apply it on stable, could you provide the commit to fix? Thanks, Gregory
quoted hunk
Signed-off-by: Jan Luebbe <jlu@pengutronix.de> --- drivers/bus/mvebu-mbus.c | 2 +- include/linux/mbus.h | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-)diff --git a/drivers/bus/mvebu-mbus.c b/drivers/bus/mvebu-mbus.c index c7f396903184..70db4d5638a6 100644 --- a/drivers/bus/mvebu-mbus.c +++ b/drivers/bus/mvebu-mbus.c@@ -720,7 +720,7 @@ mvebu_mbus_default_setup_cpu_target(struct mvebu_mbus_state *mbus) if (mbus->hw_io_coherency) w->mbus_attr |= ATTR_HW_COHERENCY; w->base = base & DDR_BASE_CS_LOW_MASK; - w->size = (size | ~DDR_SIZE_MASK) + 1; + w->size = (u64)(size | ~DDR_SIZE_MASK) + 1; } } mvebu_mbus_dram_info.num_cs = cs;diff --git a/include/linux/mbus.h b/include/linux/mbus.h index 0d3f14fd2621..4773145246ed 100644 --- a/include/linux/mbus.h +++ b/include/linux/mbus.h@@ -31,8 +31,8 @@ struct mbus_dram_target_info struct mbus_dram_window { u8 cs_index; u8 mbus_attr; - u32 base; - u32 size; + u64 base; + u64 size; } cs[4]; };-- 2.11.0
-- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com