From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752317AbdFVCVJ (ORCPT ); Wed, 21 Jun 2017 22:21:09 -0400 Received: from mailgw02.mediatek.com ([210.61.82.184]:1158 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751223AbdFVCVI (ORCPT ); Wed, 21 Jun 2017 22:21:08 -0400 Message-ID: <1498098064.717.12.camel@mtksdaap41> Subject: Re: [PATCH v2] drm: mediatek: change the variable type of rdma threshold From: Bibby Hsieh To: CK Hu CC: David Airlie , Matthias Brugger , Daniel Vetter , , , Yingjoe Chen , Cawa Cheng , Daniel Kurtz , "Philipp Zabel" , YT Shen , "Thierry Reding" , Mao Huang , , , "Sascha Hauer" Date: Thu, 22 Jun 2017 10:21:04 +0800 In-Reply-To: <1495431964.20811.8.camel@mtksdaap41> References: <1495187843-6882-1-git-send-email-bibby.hsieh@mediatek.com> <1495431964.20811.8.camel@mtksdaap41> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, CK, Thanks for your review and comment. On Mon, 2017-05-22 at 13:46 +0800, CK Hu wrote: > Hi, Bibby: > > One comment inline. > > On Fri, 2017-05-19 at 17:57 +0800, Bibby Hsieh wrote: > > For some greater resolution, the rdma threshold > > variable will overflow. > > > > Signed-off-by: Bibby Hsieh > > --- > > drivers/gpu/drm/mediatek/mtk_disp_rdma.c | 7 ++++--- > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c > > index 0df05f9..9afdcd7 100644 > > --- a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c > > +++ b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c > > @@ -37,7 +37,7 @@ > > #define DISP_REG_RDMA_FIFO_CON 0x0040 > > #define RDMA_FIFO_UNDERFLOW_EN BIT(31) > > #define RDMA_FIFO_PSEUDO_SIZE(bytes) (((bytes) / 16) << 16) > > -#define RDMA_OUTPUT_VALID_FIFO_THRESHOLD(bytes) ((bytes) / 16) > > +#define RDMA_OUTPUT_VALID_FIFO_THRESHOLD(bytes) (((bytes) / 16) & 0x3ff) > > I think it's not necessary to do this mask operation. Before calling > RDMA_OUTPUT_VALID_FIFO_THRESHOLD(), you should make sure that width, > height, and vrefresh matches the HW spec, so the result of threshold > likely does not exceed 0x3ff. If width, height, and vrefresh matches the > HW spec but threshold exceed 0x3ff, maybe you should limited it to 0x3ff > rather than truncating it. > Ok, It seems to me that I will refer Guenter's comment, add clamp_val() to avoid unexpected value. Thanks. Bibby > Regards, > CK > > > > > /** > > * struct mtk_disp_rdma - DISP_RDMA driver structure > > @@ -109,7 +109,7 @@ static void mtk_rdma_config(struct mtk_ddp_comp *comp, unsigned int width, > > unsigned int height, unsigned int vrefresh, > > unsigned int bpc) > > { > > - unsigned int threshold; > > + unsigned long long threshold; > > unsigned int reg; > > > > rdma_update_bits(comp, DISP_REG_RDMA_SIZE_CON_0, 0xfff, width); > > @@ -121,7 +121,8 @@ static void mtk_rdma_config(struct mtk_ddp_comp *comp, unsigned int width, > > * output threshold to 6 microseconds with 7/6 overhead to > > * account for blanking, and with a pixel depth of 4 bytes: > > */ > > - threshold = width * height * vrefresh * 4 * 7 / 1000000; > > + threshold = (unsigned long long)width * height * vrefresh * > > + 4 * 7 / 1000000; > > reg = RDMA_FIFO_UNDERFLOW_EN | > > RDMA_FIFO_PSEUDO_SIZE(SZ_8K) | > > RDMA_OUTPUT_VALID_FIFO_THRESHOLD(threshold); > > -- Bibby