Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753882AbdL1N6Z (ORCPT ); Thu, 28 Dec 2017 08:58:25 -0500 Received: from outils.crapouillou.net ([89.234.176.41]:50428 "EHLO crapouillou.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753672AbdL1N5F (ORCPT ); Thu, 28 Dec 2017 08:57:05 -0500 From: Paul Cercueil To: Ralf Baechle , Rob Herring , Michael Turquette Cc: Mark Rutland , Stephen Boyd , Maarten ter Huurne , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, linux-clk@vger.kernel.org Subject: [PATCH v4 13/15] MIPS: JZ4770: Workaround for corrupted DMA transfers Date: Thu, 28 Dec 2017 14:56:32 +0100 Message-Id: <20171228135634.30000-14-paul@crapouillou.net> In-Reply-To: <20171228135634.30000-1-paul@crapouillou.net> References: <20170702163016.6714-2-paul@crapouillou.net> <20171228135634.30000-1-paul@crapouillou.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2122 Lines: 79 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 diff --git a/arch/mips/jz4740/setup.c b/arch/mips/jz4740/setup.c index afd84ee966e8..6948b133a15d 100644 --- a/arch/mips/jz4740/setup.c +++ b/arch/mips/jz4740/setup.c @@ -23,6 +23,7 @@ #include #include +#include #include #include @@ -102,6 +103,29 @@ 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; + } +} + static int __init jz4740_machine_setup(void) { mips_machine_setup(); 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