Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753806AbcKORKJ (ORCPT ); Tue, 15 Nov 2016 12:10:09 -0500 Received: from mail-yb0-f173.google.com ([209.85.213.173]:34977 "EHLO mail-yb0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751599AbcKORKI (ORCPT ); Tue, 15 Nov 2016 12:10:08 -0500 MIME-Version: 1.0 In-Reply-To: <1478168250-30858-1-git-send-email-jay.xu@rock-chips.com> References: <1478168250-30858-1-git-send-email-jay.xu@rock-chips.com> From: Sean Paul Date: Tue, 15 Nov 2016 09:09:44 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] drm/bridge: analogix_dp: return error if transfer none byte To: Jianqun Xu Cc: Dave Airlie , =?UTF-8?B?546L5b6B5aKe?= , Tomeu Vizoso , Heiko Stuebner , huangtao@rock-chips.com, Masahiro Yamada , dri-devel , Linux Kernel Mailing List , linux-rockchip@lists.infradead.org, Archit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1834 Lines: 47 On Thu, Nov 3, 2016 at 3:17 AM, Jianqun Xu wrote: > Reference from drm_dp_aux description (about transfer): > Upon success, the implementation should return the number of payload bytes > that were transferred, or a negative error-code on failure. Helpers > propagate errors from the .transfer() function, with the exception of > the -EBUSY error, which causes a transaction to be retried. On a short, > helpers will return -EPROTO to make it simpler to check for failure. > > The analogix_dp_transfer will return num_transferred, but if there is none > byte been transferred, the return value will be 0, which means success, we > should return error-code if transfer none byte. > > for (retry = 0; retry < 32; retry++) { > err = aux->transfer(aux, &msg); > if (err < 0) { > if (err == -EBUSY) > continue; > > goto unlock; > } > } > > Cc: zain wang > Cc: Sean Paul > Signed-off-by: Jianqun Xu Reviewed-by: Sean Paul > --- > drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c > index cd37ac0..303083a 100644 > --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c > +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c > @@ -1162,5 +1162,5 @@ ssize_t analogix_dp_transfer(struct analogix_dp_device *dp, > (msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_NATIVE_READ) > msg->reply = DP_AUX_NATIVE_REPLY_ACK; > > - return num_transferred; > + return num_transferred > 0 ? num_transferred : -EBUSY; > } > -- > 1.9.1 > >