From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcin Nowakowski Subject: Re: [PATCH v2 15/17] MIPS: JZ4770: Workaround for corrupted DMA transfers Date: Thu, 22 Jun 2017 09:21:02 +0200 Message-ID: References: <20170607200439.24450-2-paul@crapouillou.net> <20170620151855.19399-1-paul@crapouillou.net> <20170620151855.19399-15-paul@crapouillou.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170620151855.19399-15-paul-icTtO2rgO2OTuSrc4Mpeew@public.gmane.org> Content-Language: en-US Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Paul Cercueil , Ralf Baechle , Michael Turquette , Stephen Boyd , Rob Herring Cc: Paul Burton , Maarten ter Huurne , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mips-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org, linux-clk-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Paul, Maarten, On 20.06.2017 17:18, Paul Cercueil wrote: > 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 > > 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 89785600fde4..cccfd7ba89fe 100644 > --- a/arch/mips/kernel/setup.c > +++ b/arch/mips/kernel/setup.c > @@ -838,6 +838,14 @@ 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 > + This part doesn't look good in the platform-agnostic code ... is there a reason why you wouldn't do that from within plat_mem_setup()? > if (usermem) { > pr_info("User-defined physical RAM map:\n"); > print_memory_map(); > Marcin -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html