From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-oi0-x243.google.com ([2607:f8b0:4003:c06::243]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1dfpRr-0001Ms-CB for barebox@lists.infradead.org; Thu, 10 Aug 2017 15:32:37 +0000 Received: by mail-oi0-x243.google.com with SMTP id q70so929124oic.2 for ; Thu, 10 Aug 2017 08:32:14 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <7360e7wsyx.fsf@pengutronix.de> From: Mabcded Babcde Date: Thu, 10 Aug 2017 17:32:12 +0200 Message-ID: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH] Add new command fs2bridge for socfpga To: Steffen Trumtrar Cc: Andrey Smirnov , "barebox@lists.infradead.org" 2017-08-04 15:13 GMT+02:00 Mabcded Babcde : > 2017-08-01 11:13 GMT+02:00 Steffen Trumtrar : >> >> Hi! >> >> Andrey Smirnov writes: >> >>> On Sun, Jul 30, 2017 at 2:17 PM, Mabcded Babcde >>> wrote: >>>> 2017-07-28 15:42 GMT+02:00 Andrey Smirnov : >>>>> On Fri, Jul 28, 2017 at 6:24 AM, Mabcded Babcde >>>>> wrote: >>>>>> 2017-07-27 20:49 GMT+02:00 Andrey Smirnov : >>>>>>> On Thu, Jul 27, 2017 at 9:20 AM, Mabcded Babcde >>>>>>> wrote: >>>>>>>> Hi, >>>>>>>> this patch adds a new command to barebox. It is used to enable or >>>>>>>> disable the fpga-to-sdram bridges on socfpgas. The patch is based on a >>>>>>>> manual from altera >>>>>>>> (https://www.altera.com/support/support-resources/knowledge-base/embedded/2016/how-and-when-can-i-enable-the-fpga2sdram-bridge-on-cyclone-v-soc.html) >>>>>>>> and a implementation for u-boot >>>>>>>> (https://github.com/rogerq/u-boot/blob/master/arch/arm/mach-socfpga/misc.c). >>>>>>>> The fpga2sdram fpga configuration can only be set when the SDRAM >>>>>>>> interface is idle. So it is necessary to use the on-chip ram. >>>>>>> >>>>>>> And by "on-chip ram" you mean i-cache and not SRAM block used by first >>>>>>> stage bootloader, correct? I am just a bit confused by the wording. >>>>>>> >>>>>> >>>>>> Sorry, my fault. I meant i-cache. >>>>>> >>>>>>>> To bring all fpga2sdram bridges out of reset it is necessary to write 0x3FFF to >>>>>>>> the register. Only the fpga2sdram bridges are enabled or disabled but >>>>>>>> no other bridges like the axi bridges. >>>>>>> >>>>>>> Linux kernel already has: >>>>>>> >>>>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/fpga/altera-fpga2sdram-bridge.txt?h=v4.13-rc2 >>>>>>> >>>>>>> so, IMHO, it would be better to implement a compatible driver and, if >>>>>>> ability to change the value at run-time is needed, add "enable" >>>>>>> property to it rather than introducing a separate command. >>>>>>> >>>>>> >>>>>> But how can I ensure that the SDRAM is idle? I quote Altera: >>>>>> "First time enabling of the FPGA2SDRAM bridge within Linux is not >>>>>> supported as the SDRAM subsystem cannot be easily put into a >>>>>> guaranteed idle state." >>>>>> >>>>> >>>>> I feel like we are talking about different things. What I am trying to >>>>> say that instead of adding this functionality to Barebox as a >>>>> standalone command, it would be better to add it _to Barebox_ as a >>>>> driver that claims compatibility with "altr,socfpga-fpga2sdram-bridge" >>>>> and implements all of the necessary logic there. It would be the same >>>>> code running in the boot-loader but triggered to executed via >>>>> different means, so it should literally be the same in terms of SDRAM >>>>> access quiescence. A somewhat relative example of that approach would >>>>> be "drivers/firmware/socfpga.c". >>>> >>>> Ok, I hardcoded my code from the command to drivers/firmware/socfpga.c >>>> for testing purposes. That didn't seem to work. >>> >>> I'd double check that CONFIG_FIRMWARE and >>> CONFIG_FIRMWARE_ALTERA_SOCFPGA are set to "y". >>> >>>> However how would I >>>> enable or disable the bridge? With a parameter? Where can I add it and >>>> change it? >>>> >>>>> >>> >>> The driver in firmware/socfpga.c should create a "fpga0" device, after >>> which, you cat set that device's variables/attributes by simply doing: >>> >>> fpga0.variable_name = value >>> >>> and get them via >>> >>> echo ${fpga0.variable_name} >>> >> >> The right approach should be adding a proper bridge driver like in the >> kernel. Then in the fpgamgr_program_finish enable all registered >> bridges. And set the APPFLYCFG bit in the bridge driver. >> Or do I miss something? >> >> The cacheline magic seems rather fragile and therefore just running a >> function (with almost the same assembler code) from OCRAM seems to be the >> more robust option. >> >> As a matter of fact, I already have the bridge drivers ported to >> barebox. I can post the series as an RFC as I haven't tested it since I >> rebased it to v2017.07.0. > > I built Barebox successfully with your drivers, but the fpga-bridge > wasn't enabled. And where is the OCRAM part in your driver? In socfpga-fpgasdram-bridge.c ALT_SDR_CTL_FPGAPORTRST_PORTRSTN_MSK is defined, but not used. In the same file the socfpga_sdram_apply_staticcfg part is missing in static inline int _alt_fpga2sdram_enable_set(struct alt_fpga2sdram_data *priv, bool enable) > >> >> >> Regards, >> Steffen >> >> -- >> Pengutronix e.K. | Steffen Trumtrar | >> Industrial Linux Solutions | http://www.pengutronix.de/ | >> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | >> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | Best regards, Mathieu _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox