From 885dbd154b2f2ee305cec6fd0a162e1a77ae2b06 Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Thu, 28 May 2015 10:40:13 +0200 Subject: [PATCH] Revert "bus: mvebu-mbus: make sure SDRAM CS for DMA don't overlap the MBus bridge window" This reverts commit 1737cac69369 ("bus: mvebu-mbus: make sure SDRAM CS for DMA don't overlap the MBus bridge window"), because it breaks DMA on platforms having more than 2 GB of RAM. This commit changed the information reported to DMA masters device drivers through the mv_mbus_dram_info() function so that the returned DRAM ranges do not overlap with I/O windows. This was necessary as a preparation to support the new CESA Crypto Engine driver, which will use DMA for cryptographic operations. But since it does DMA with the SRAM which is mapped as an I/O window, having DRAM ranges overlapping with I/O windows was problematic. To solve this, the above mentioned commit changed the mvebu-mbus to adjust the DRAM ranges so that they don't overlap with the I/O windows. However, by doing this, we re-adjust the DRAM ranges in a way that makes them have a size that is no longer a power of two. While this is perfectly fine for the Crypto Engine, which supports DRAM ranges with a granularity of 64 KB, it breaks basically all other DMA masters, which expect power of two sizes for the DRAM ranges. Due to this, if the installed system memory is 4 GB, in two chip-selects of 2 GB, the second DRAM range will be reduced from 2 GB to a little bit less than 2 GB to not overlap with the I/O windows, in a way that results in a DRAM range that doesn't have a power of two size. This means that whenever you do a DMA transfer with an address located in the [ 2 GB ; 4 GB ] area, it will freeze the system. Any serious DMA activity like simply running: for i in $(seq 1 64) ; do dd if=/dev/urandom of=file$i bs=1M count=16 ; done in an ext3 partition mounted over a SATA drive will freeze the system. Since the new CESA crypto driver that uses DMA has not been merged yet, the easiest fix is to simply revert this commit. A follow-up commit will introduce a different solution for the CESA crypto driver. Signed-off-by: Thomas Petazzoni Fixes: 1737cac69369 ("bus: mvebu-mbus: make sure SDRAM CS for DMA don't overlap the MBus bridge window") Cc: # v4.0+ Signed-off-by: Gregory CLEMENT --- drivers/bus/mvebu-mbus.c | 105 ++++++--------------------------------- 1 file changed, 16 insertions(+), 89 deletions(-) diff --git a/drivers/bus/mvebu-mbus.c b/drivers/bus/mvebu-mbus.c index 7fa4510dfbe4..6f047dcb94c2 100644 --- a/drivers/bus/mvebu-mbus.c +++ b/drivers/bus/mvebu-mbus.c @@ -58,7 +58,6 @@ #include #include #include -#include /* * DDR target is the same on all platforms. @@ -103,9 +102,7 @@ /* Relative to mbusbridge_base */ #define MBUS_BRIDGE_CTRL_OFF 0x0 -#define MBUS_BRIDGE_SIZE_MASK 0xffff0000 #define MBUS_BRIDGE_BASE_OFF 0x4 -#define MBUS_BRIDGE_BASE_MASK 0xffff0000 /* Maximum number of windows, for all known platforms */ #define MBUS_WINS_MAX 20 @@ -579,106 +576,36 @@ static unsigned int armada_xp_mbus_win_remap_offset(int win) return MVEBU_MBUS_NO_REMAP; } -/* - * Use the memblock information to find the MBus bridge hole in the - * physical address space. - */ -static void __init -mvebu_mbus_find_bridge_hole(uint64_t *start, uint64_t *end) -{ - struct memblock_region *r; - uint64_t s = 0; - - for_each_memblock(memory, r) { - /* - * This part of the memory is above 4 GB, so we don't - * care for the MBus bridge hole. - */ - if (r->base >= 0x100000000) - continue; - - /* - * The MBus bridge hole is at the end of the RAM under - * the 4 GB limit. - */ - if (r->base + r->size > s) - s = r->base + r->size; - } - - *start = s; - *end = 0x100000000; -} - static void __init mvebu_mbus_default_setup_cpu_target(struct mvebu_mbus_state *mbus) { int i; int cs; - uint64_t mbus_bridge_base, mbus_bridge_end; mvebu_mbus_dram_info.mbus_dram_target_id = TARGET_DDR; - mvebu_mbus_find_bridge_hole(&mbus_bridge_base, &mbus_bridge_end); - for (i = 0, cs = 0; i < 4; i++) { - u64 base = readl(mbus->sdramwins_base + DDR_BASE_CS_OFF(i)); - u64 size = readl(mbus->sdramwins_base + DDR_SIZE_CS_OFF(i)); - u64 end; - struct mbus_dram_window *w; - - /* Ignore entries that are not enabled */ - if (!(size & DDR_SIZE_ENABLED)) - continue; + u32 base = readl(mbus->sdramwins_base + DDR_BASE_CS_OFF(i)); + u32 size = readl(mbus->sdramwins_base + DDR_SIZE_CS_OFF(i)); /* - * Ignore entries whose base address is above 2^32, - * since devices cannot DMA to such high addresses + * We only take care of entries for which the chip + * select is enabled, and that don't have high base + * address bits set (devices can only access the first + * 32 bits of the memory). */ - if (base & DDR_BASE_CS_HIGH_MASK) - continue; + if ((size & DDR_SIZE_ENABLED) && + !(base & DDR_BASE_CS_HIGH_MASK)) { + struct mbus_dram_window *w; - base = base & DDR_BASE_CS_LOW_MASK; - size = (size | ~DDR_SIZE_MASK) + 1; - end = base + size; - - /* - * Adjust base/size of the current CS to make sure it - * doesn't overlap with the MBus bridge hole. This is - * particularly important for devices that do DMA from - * DRAM to a SRAM mapped in a MBus window, such as the - * CESA cryptographic engine. - */ - - /* - * The CS is fully enclosed inside the MBus bridge - * area, so ignore it. - */ - if (base >= mbus_bridge_base && end <= mbus_bridge_end) - continue; - - /* - * Beginning of CS overlaps with end of MBus, raise CS - * base address, and shrink its size. - */ - if (base >= mbus_bridge_base && end > mbus_bridge_end) { - size -= mbus_bridge_end - base; - base = mbus_bridge_end; + w = &mvebu_mbus_dram_info.cs[cs++]; + w->cs_index = i; + w->mbus_attr = 0xf & ~(1 << i); + 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; } - - /* - * End of CS overlaps with beginning of MBus, shrink - * CS size. - */ - if (base < mbus_bridge_base && end > mbus_bridge_base) - size -= end - mbus_bridge_base; - - w = &mvebu_mbus_dram_info.cs[cs++]; - w->cs_index = i; - w->mbus_attr = 0xf & ~(1 << i); - if (mbus->hw_io_coherency) - w->mbus_attr |= ATTR_HW_COHERENCY; - w->base = base; - w->size = size; } mvebu_mbus_dram_info.num_cs = cs; }