Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752662AbeAESZh (ORCPT + 1 other); Fri, 5 Jan 2018 13:25:37 -0500 Received: from outils.crapouillou.net ([89.234.176.41]:56654 "EHLO crapouillou.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752633AbeAESZe (ORCPT ); Fri, 5 Jan 2018 13:25:34 -0500 From: Paul Cercueil To: Ralf Baechle Cc: Maarten ter Huurne , Paul Burton , linux-kernel@vger.kernel.org, linux-mips@linux-mips.org Subject: [PATCH v6 13/15] MIPS: JZ4770: Workaround for corrupted DMA transfers Date: Fri, 5 Jan 2018 19:25:11 +0100 Message-Id: <20180105182513.16248-14-paul@crapouillou.net> In-Reply-To: <20180105182513.16248-1-paul@crapouillou.net> References: <20180102150848.11314-1-paul@crapouillou.net> <20180105182513.16248-1-paul@crapouillou.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Maarten ter Huurne We have seen MMC DMA transfers read corrupted data from SDRAM when a burst interval ends at physical address 0x10000000. To avoid this problem, we remove the final page of low memory from the memory map. Signed-off-by: Maarten ter Huurne --- arch/mips/jz4740/setup.c | 24 ++++++++++++++++++++++++ arch/mips/kernel/setup.c | 8 ++++++++ 2 files changed, 32 insertions(+) v2: No change v3: No change v4: No change v5: No change v6: No change diff --git a/arch/mips/jz4740/setup.c b/arch/mips/jz4740/setup.c index cd89536fbba1..18c57c4bf47e 100644 --- a/arch/mips/jz4740/setup.c +++ b/arch/mips/jz4740/setup.c @@ -22,6 +22,7 @@ #include #include +#include #include #include @@ -103,3 +104,26 @@ void __init arch_init_irq(void) { irqchip_init(); } + +/* + * We have seen MMC DMA transfers read corrupted data from SDRAM when a burst + * interval ends at physical address 0x10000000. To avoid this problem, we + * remove the final page of low memory from the memory map. + */ +void __init jz4770_reserve_unsafe_for_dma(void) +{ + int i; + + for (i = 0; i < boot_mem_map.nr_map; i++) { + struct boot_mem_map_entry *entry = boot_mem_map.map + i; + + if (entry->type != BOOT_MEM_RAM) + continue; + + if (entry->addr + entry->size != 0x10000000) + continue; + + entry->size -= PAGE_SIZE; + break; + } +} diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c index 85bc601e9a0d..5a2c20145aee 100644 --- a/arch/mips/kernel/setup.c +++ b/arch/mips/kernel/setup.c @@ -879,6 +879,14 @@ static void __init arch_mem_init(char **cmdline_p) parse_early_param(); +#ifdef CONFIG_MACH_JZ4770 + if (current_cpu_type() == CPU_JZRISC && + mips_machtype == MACH_INGENIC_JZ4770) { + extern void __init jz4770_reserve_unsafe_for_dma(void); + jz4770_reserve_unsafe_for_dma(); + } +#endif + if (usermem) { pr_info("User-defined physical RAM map:\n"); print_memory_map(); -- 2.11.0