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([2a02:908:8b3:1840:e0a4:c719:5e8d:3b55]) by smtp.gmail.com with ESMTPSA id e11-20020a056402148b00b00529fa63ef6fsm5930777edv.57.2023.09.04.07.28.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 Sep 2023 07:28:40 -0700 (PDT) Message-ID: <53ee3d14-05f4-981f-26d2-ef9ef6b3a61b@gmail.com> Date: Mon, 4 Sep 2023 16:28:37 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH 5/5] drm/bridge: samsung-dsim: calculate porches in Hz To: Michael Tretter References: <20230818-samsung-dsim-v1-0-b39716db6b7a@pengutronix.de> <20230818-samsung-dsim-v1-5-b39716db6b7a@pengutronix.de> Content-Language: en-US From: Maxim Schwalm In-Reply-To: <20230818-samsung-dsim-v1-5-b39716db6b7a@pengutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Neil Armstrong , Jernej Skrabec , Robert Foss , Andrzej Hajda , Jonas Karlman , Laurent Pinchart , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Jagan Teki , kernel@pengutronix.de, Marek Szyprowski Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi, On 28.08.23 17:59, Michael Tretter wrote: > Calculating the byte_clk in kHz is imprecise for a hs_clock of 55687500 > Hz, which may be used with a pixel clock of 74.25 MHz with mode > 1920x1080-30. > > Fix the calculation by using HZ instead of kHZ. > > This requires to change the type to u64 to prevent overflows of the > integer type. > > Signed-off-by: Michael Tretter > --- > drivers/gpu/drm/bridge/samsung-dsim.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c > index 459be953be55..eb7aca2b9ab7 100644 > --- a/drivers/gpu/drm/bridge/samsung-dsim.c > +++ b/drivers/gpu/drm/bridge/samsung-dsim.c > @@ -973,10 +973,12 @@ static void samsung_dsim_set_display_mode(struct samsung_dsim *dsi) > u32 reg; > > if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO) { > - int byte_clk_khz = dsi->hs_clock / 1000 / 8; > - int hfp = DIV_ROUND_UP((m->hsync_start - m->hdisplay) * byte_clk_khz, m->clock); > - int hbp = DIV_ROUND_UP((m->htotal - m->hsync_end) * byte_clk_khz, m->clock); > - int hsa = DIV_ROUND_UP((m->hsync_end - m->hsync_start) * byte_clk_khz, m->clock); > + u64 byte_clk = dsi->hs_clock / 8; > + u64 pix_clk = m->clock * 1000; > + > + int hfp = DIV64_U64_ROUND_UP((m->hsync_start - m->hdisplay) * byte_clk, pix_clk); > + int hbp = DIV64_U64_ROUND_UP((m->htotal - m->hsync_end) * byte_clk, pix_clk); > + int hsa = DIV64_U64_ROUND_UP((m->hsync_end - m->hsync_start) * byte_clk, pix_clk); Wouldn't it make sense to use the videomode structure here? > > /* remove packet overhead when possible */ > hfp = max(hfp - 6, 0); > Best regards, Maxim