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Mon, 29 Apr 2024 08:08:21 +0000 (UTC) Message-ID: <57529d24-8b46-4eed-95ed-463ad3f4190e@collabora.com> Date: Mon, 29 Apr 2024 10:08:20 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 4/7] soc: mediatek: Add MediaTek DVFS Resource Collector (DVFSRC) driver To: Nathan Chancellor Cc: djakov@kernel.org, robh@kernel.org, krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, matthias.bgg@gmail.com, lgirdwood@gmail.com, broonie@kernel.org, keescook@chromium.org, gustavoars@kernel.org, henryc.chen@mediatek.com, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, kernel@collabora.com, wenst@chromium.org, amergnat@baylibre.com, Dawei Chien References: <20240424095416.1105639-1-angelogioacchino.delregno@collabora.com> <20240424095416.1105639-5-angelogioacchino.delregno@collabora.com> <20240424190405.GA2803128@dev-arch.thelio-3990X> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: <20240424190405.GA2803128@dev-arch.thelio-3990X> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Il 24/04/24 21:04, Nathan Chancellor ha scritto: > Hi Angelo, > > On Wed, Apr 24, 2024 at 11:54:13AM +0200, AngeloGioacchino Del Regno wrote: >> The Dynamic Voltage and Frequency Scaling Resource Collector (DVFSRC) is a >> Hardware module used to collect all the requests from both software and the >> various remote processors embedded into the SoC and decide about a minimum >> operating voltage and a minimum DRAM frequency to fulfill those requests in >> an effort to provide the best achievable performance per watt. >> >> This hardware IP is capable of transparently performing direct register R/W >> on all of the DVFSRC-controlled regulators and SoC bandwidth knobs. >> >> This driver includes support for MT8183, MT8192 and MT8195. >> >> Co-Developed-by: Dawei Chien >> [Angelo: Partial refactoring and cleanups] >> Signed-off-by: AngeloGioacchino Del Regno > ... >> drivers/soc/mediatek/mtk-dvfsrc.c | 551 +++++++++++++++++++++++ > ... >> +#define KBPS_TO_MBPS(x) ((x) / 1000) > ... >> +static void __dvfsrc_set_dram_bw_v1(struct mtk_dvfsrc *dvfsrc, u32 reg, >> + u16 max_bw, u16 min_bw, u64 bw) >> +{ >> + u32 new_bw = (u32)div_u64(KBPS_TO_MBPS(bw), 100); >> + >> + /* If bw constraints (in mbps) are defined make sure to respect them */ >> + if (max_bw) >> + new_bw = min(new_bw, max_bw); >> + if (min_bw && new_bw > 0) >> + new_bw = max(new_bw, min_bw); >> + >> + dvfsrc_writel(dvfsrc, reg, new_bw); >> +} > > Using KBPS_TO_MBPS here results in > > ERROR: modpost: "__aeabi_uldivmod" [drivers/soc/mediatek/mtk-dvfsrc.ko] undefined! > > when building ARCH=arm allmodconfig with clang. I did not check to see > if this is visible with GCC but if it is not, it is only because GCC > implements certain transformations for constant division that clang may > or may not have implemented (there was some work on getting all > transformations that GCC has supported in clang as well but I do not > think was ever completed). Perhaps KBPS_TO_MBPS() should be dropped and > the new_bw assignement turned into > > u32 new_bw = (u32)div_u64(bw, 100 * 1000); /* Multiply divisor by 1000 to convert bw from Kbps to Mbps */ Thanks, I honestly didn't check clang. Your suggestion looks good, I'll do exactly that. Cheers! Angelo > > or something like that. > > Cheers, > Nathan