From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jian Luo Date: Tue, 1 Sep 2015 14:32:26 +0200 Subject: [U-Boot] arm: socfpga: Question about FPGA/HPS SDRAM Bridge In-Reply-To: <201509011403.22313.marex@denx.de> References: <55E564BB.3090505@boschrexroth.de> <201509011103.48529.marex@denx.de> <55E590D7.7010103@boschrexroth.de> <201509011403.22313.marex@denx.de> Message-ID: <55E59ADA.3080403@boschrexroth.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Marek, On 01.09.2015 14:03, Marek Vasut wrote: > On Tuesday, September 01, 2015 at 01:49:43 PM, Jian Luo wrote: ----snip---- >> What about calling socfpga_sdram_apply_static_cfg() direct in >> socfpga_load() in drivers/fpga/socfpga.c to make it generic? > > Which code exactly do you refer to ? I mean something like this. diff --git a/drivers/fpga/socfpga.c b/drivers/fpga/socfpga.c index 4448250..d0f67f6 100644 --- a/drivers/fpga/socfpga.c +++ b/drivers/fpga/socfpga.c @@ -300,5 +300,12 @@ int socfpga_load(Altera_desc *desc, const void *rbf_data, size_t rbf_size) return status; /* Ensure the FPGA entering user mode */ - return fpgamgr_program_poll_usermode(); + status = fpgamgr_program_poll_usermode(); + if (status) + return status; + + /* Latch FPGA2SDRAM bridge configuration */ + socfpga_sdram_apply_static_cfg(); + + return 0; } > >> socfpga_load() already did step 1 and 2. >> Is there any side effect when fpga2sdram bridge is not used? > > The idea is to keep the FPGA programming code and the code which controls > the bridges separate. The reason for that is that you can have content in > the FPGA which is running completely independent of the HPS software. You > don't always need to enable the bridges. No, it's the other way around here. socfpga_load() runs eventually when command "fpga load" is called. So when I explicitly use "fpga load" command, the old FPGA program is expected to stop running, right? And I don't want to enable the bridge here, just to latch the SDRAM configuration. > > The FPGA2SDRAM bridge (or, more like fpga2hps bridge) is used for stuff > like framebuffers implemented in the FPGA, so that the FPGA can fetch > data from the SDRAM. > > Best regards, > Marek Vasut Best regards, Jian Luo