Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755161AbaGDF5o (ORCPT ); Fri, 4 Jul 2014 01:57:44 -0400 Received: from mail-ve0-f180.google.com ([209.85.128.180]:43161 "EHLO mail-ve0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752162AbaGDF5m (ORCPT ); Fri, 4 Jul 2014 01:57:42 -0400 MIME-Version: 1.0 In-Reply-To: <53B5131B.1060702@samsung.com> References: <1404303560-32209-1-git-send-email-acourbot@nvidia.com> <1404303560-32209-2-git-send-email-acourbot@nvidia.com> <53B5131B.1060702@samsung.com> From: Alexandre Courbot Date: Fri, 4 Jul 2014 14:57:21 +0900 Message-ID: Subject: Re: [PATCH 1/4] drm/dsi: Add flag for continuous clock behavior To: Andrzej Hajda Cc: Alexandre Courbot , Thierry Reding , Terje Bergstrom , Stephen Warren , "linux-tegra@vger.kernel.org" , Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andrejz, On Thu, Jul 3, 2014 at 5:23 PM, Andrzej Hajda wrote: > > Hi Alexandre, > > Thanks for the patch. > > On 07/02/2014 02:19 PM, Alexandre Courbot wrote: >> As per section 5.6.1 of the DSI specification, all DSI transmitters must >> support continuous clock behavior on the clock lane, while non-continuous >> mode support is only optional. Add a flag that allows devices to indicate >> that they require continuous clock mode to operate properly. >> >> Signed-off-by: Alexandre Courbot >> --- >> include/drm/drm_mipi_dsi.h | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h >> index 944f33f..5913ef4 100644 >> --- a/include/drm/drm_mipi_dsi.h >> +++ b/include/drm/drm_mipi_dsi.h >> @@ -94,6 +94,8 @@ void mipi_dsi_host_unregister(struct mipi_dsi_host *host); >> #define MIPI_DSI_MODE_VSYNC_FLUSH BIT(8) >> /* disable EoT packets in HS mode */ >> #define MIPI_DSI_MODE_EOT_PACKET BIT(9) >> +/* use continuous clock behavior on the clock lane */ >> +#define MIPI_DSI_MODE_CLOCK_CONTINUOUS BIT(10) >> > > According to MIPI DSI specification "All DSI transmitters and receivers > shall support continuous clock behavior on the Clock Lane, and > optionally may support non-continuous clock behavior". It suggests that > continuous clock should be default behavior. So maybe better is to > introduce sth like: > +#define MIPI_DSI_MODE_CLOCK_NON_CONTINUOUS BIT(10) I started under the assumption that current host drivers assumed non-continuous clock (as the Tegra driver currently does). In that light, it seemed to make sense (and to be less intrusive) to introduce that flag as a restriction rather than a capability. But if you think this should be a capability I am not strongly against it - either way, host drivers need to be changed to take that flag into account. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/