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[90.63.244.31]) by smtp.gmail.com with ESMTPSA id x25sm1402445wmc.36.2019.06.07.07.11.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Jun 2019 07:11:25 -0700 (PDT) Subject: Re: [PATCH 2/5] drm/bridge: add encoder support to specify bridge input format To: Laurent Pinchart References: <20190520133753.23871-1-narmstrong@baylibre.com> <20190520133753.23871-3-narmstrong@baylibre.com> <20190607133818.GM7593@pendragon.ideasonboard.com> From: Neil Armstrong Openpgp: preference=signencrypt Autocrypt: addr=narmstrong@baylibre.com; prefer-encrypt=mutual; keydata= mQENBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAG0KE5laWwgQXJtc3Ryb25nIDxuYXJtc3Ryb25nQGJheWxpYnJlLmNvbT6JATsEEwEKACUC GyMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheABQJXDO2CAhkBAAoJEBaat7Gkz/iubGIH/iyk RqvgB62oKOFlgOTYCMkYpm2aAOZZLf6VKHKc7DoVwuUkjHfIRXdslbrxi4pk5VKU6ZP9AKsN NtMZntB8WrBTtkAZfZbTF7850uwd3eU5cN/7N1Q6g0JQihE7w4GlIkEpQ8vwSg5W7hkx3yQ6 2YzrUZh/b7QThXbNZ7xOeSEms014QXazx8+txR7jrGF3dYxBsCkotO/8DNtZ1R+aUvRfpKg5 ZgABTC0LmAQnuUUf2PHcKFAHZo5KrdO+tyfL+LgTUXIXkK+tenkLsAJ0cagz1EZ5gntuheLD YJuzS4zN+1Asmb9kVKxhjSQOcIh6g2tw7vaYJgL/OzJtZi6JlIW5AQ0ETVkGzwEIALyKDN/O GURaHBVzwjgYq+ZtifvekdrSNl8TIDH8g1xicBYpQTbPn6bbSZbdvfeQPNCcD4/EhXZuhQXM coJsQQQnO4vwVULmPGgtGf8PVc7dxKOeta+qUh6+SRh3vIcAUFHDT3f/Zdspz+e2E0hPV2hi SvICLk11qO6cyJE13zeNFoeY3ggrKY+IzbFomIZY4yG6xI99NIPEVE9lNBXBKIlewIyVlkOa YvJWSV+p5gdJXOvScNN1epm5YHmf9aE2ZjnqZGoMMtsyw18YoX9BqMFInxqYQQ3j/HpVgTSv mo5ea5qQDDUaCsaTf8UeDcwYOtgI8iL4oHcsGtUXoUk33HEAEQEAAYkBHwQYAQIACQUCTVkG zwIbDAAKCRAWmrexpM/4rrXiB/sGbkQ6itMrAIfnM7IbRuiSZS1unlySUVYu3SD6YBYnNi3G 5EpbwfBNuT3H8//rVvtOFK4OD8cRYkxXRQmTvqa33eDIHu/zr1HMKErm+2SD6PO9umRef8V8 2o2oaCLvf4WeIssFjwB0b6a12opuRP7yo3E3gTCSKmbUuLv1CtxKQF+fUV1cVaTPMyT25Od+ RC1K+iOR0F54oUJvJeq7fUzbn/KdlhA8XPGzwGRy4zcsPWvwnXgfe5tk680fEKZVwOZKIEuJ C3v+/yZpQzDvGYJvbyix0lHnrCzq43WefRHI5XTTQbM0WUIBIcGmq38+OgUsMYu4NzLu7uZF Acmp6h8guQINBFYnf6QBEADQ+wBYa+X2n/xIQz/RUoGHf84Jm+yTqRT43t7sO48/cBW9vAn9 GNwnJ3HRJWKATW0ZXrCr40ES/JqM1fUTfiFDB3VMdWpEfwOAT1zXS+0rX8yljgsWR1UvqyEP 3xN0M/40Zk+rdmZKaZS8VQaXbveaiWMEmY7sBV3QvgOzB7UF2It1HwoCon5Y+PvyE3CguhBd 9iq5iEampkMIkbA3FFCpQFI5Ai3BywkLzbA3ZtnMXR8Qt9gFZtyXvFQrB+/6hDzEPnBGZOOx zkd/iIX59SxBuS38LMlhPPycbFNmtauOC0DNpXCv9ACgC9tFw3exER/xQgSpDVc4vrL2Cacr wmQp1k9E0W+9pk/l8S1jcHx03hgCxPtQLOIyEu9iIJb27TjcXNjiInd7Uea195NldIrndD+x 58/yU3X70qVY+eWbqzpdlwF1KRm6uV0ZOQhEhbi0FfKKgsYFgBIBchGqSOBsCbL35f9hK/JC 6LnGDtSHeJs+jd9/qJj4WqF3x8i0sncQ/gszSajdhnWrxraG3b7/9ldMLpKo/OoihfLaCxtv xYmtw8TGhlMaiOxjDrohmY1z7f3rf6njskoIXUO0nabun1nPAiV1dpjleg60s3OmVQeEpr3a K7gR1ljkemJzM9NUoRROPaT7nMlNYQL+IwuthJd6XQqwzp1jRTGG26J97wARAQABiQM+BBgB AgAJBQJWJ3+kAhsCAikJEBaat7Gkz/iuwV0gBBkBAgAGBQJWJ3+kAAoJEHfc29rIyEnRk6MQ AJDo0nxsadLpYB26FALZsWlN74rnFXth5dQVQ7SkipmyFWZhFL8fQ9OiIoxWhM6rSg9+C1w+ n45eByMg2b8H3mmQmyWztdI95OxSREKwbaXVapCcZnv52JRjlc3DoiiHqTZML5x1Z7lQ1T3F 8o9sKrbFO1WQw1+Nc91+MU0MGN0jtfZ0Tvn/ouEZrSXCE4K3oDGtj3AdC764yZVq6CPigCgs 6Ex80k6QlzCdVP3RKsnPO2xQXXPgyJPJlpD8bHHHW7OLfoR9DaBNympfcbQJeekQrTvyoASw EOTPKE6CVWrcQIztUp0WFTdRGgMK0cZB3Xfe6sOp24PQTHAKGtjTHNP/THomkH24Fum9K3iM /4Wh4V2eqGEgpdeSp5K+LdaNyNgaqzMOtt4HYk86LYLSHfFXywdlbGrY9+TqiJ+ZVW4trmui NIJCOku8SYansq34QzYM0x3UFRwff+45zNBEVzctSnremg1mVgrzOfXU8rt+4N1b2MxorPF8 619aCwVP7U16qNSBaqiAJr4e5SNEnoAq18+1Gp8QsFG0ARY8xp+qaKBByWES7lRi3QbqAKZf yOHS6gmYo9gBmuAhc65/VtHMJtxwjpUeN4Bcs9HUpDMDVHdfeRa73wM+wY5potfQ5zkSp0Jp bxnv/cRBH6+c43stTffprd//4Hgz+nJcCgZKtCYIAPkUxABC85ID2CidzbraErVACmRoizhT KR2OiqSLW2x4xdmSiFNcIWkWJB6Qdri0Fzs2dHe8etD1HYaht1ZhZ810s7QOL7JwypO8dscN KTEkyoTGn6cWj0CX+PeP4xp8AR8ot4d0BhtUY34UPzjE1/xyrQFAdnLd0PP4wXxdIUuRs0+n WLY9Aou/vC1LAdlaGsoTVzJ2gX4fkKQIWhX0WVk41BSFeDKQ3RQ2pnuzwedLO94Bf6X0G48O VsbXrP9BZ6snXyHfebPnno/te5XRqZTL9aJOytB/1iUna+1MAwBxGFPvqeEUUyT+gx1l3Acl ZaTUOEkgIor5losDrePdPgE= Organization: Baylibre Message-ID: Date: Fri, 7 Jun 2019 16:11:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190607133818.GM7593@pendragon.ideasonboard.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190607_071128_004245_4589DD96 X-CRM114-Status: GOOD ( 28.60 ) X-BeenThere: linux-amlogic@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jernej.skrabec@siol.net, jonas@kwiboo.se, maxime.ripard@bootlin.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, hverkuil@xs4all.nl, a.hajda@samsung.com, linux-amlogic@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-amlogic" Errors-To: linux-amlogic-bounces+linux-amlogic=archiver.kernel.org@lists.infradead.org On 07/06/2019 15:38, Laurent Pinchart wrote: > Hi Neil, > > Thank you for the patch. > > On Mon, May 20, 2019 at 03:37:50PM +0200, Neil Armstrong wrote: >> This patch adds a new format_set() callback to the bridge ops permitting >> the encoder to specify the new input format and encoding. >> >> This allows supporting the very specific HDMI2.0 YUV420 output mode >> when the bridge cannot convert from RGB or YUV444 to YUV420. >> >> In this case, the encode must downsample before the bridge and must >> specify the bridge the new input bus format differs. >> >> This will also help supporting the YUV420 mode where the bridge cannot >> downsample, and also support 10bit, 12bit and 16bit output modes >> when the bridge cannot convert between different bit depths. >> >> Signed-off-by: Neil Armstrong >> --- >> drivers/gpu/drm/drm_bridge.c | 35 +++++++++++++++++++++++++++++++++++ >> include/drm/drm_bridge.h | 19 +++++++++++++++++++ >> 2 files changed, 54 insertions(+) >> >> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c >> index 138b2711d389..33be74a977f7 100644 >> --- a/drivers/gpu/drm/drm_bridge.c >> +++ b/drivers/gpu/drm/drm_bridge.c >> @@ -307,6 +307,41 @@ void drm_bridge_mode_set(struct drm_bridge *bridge, >> } >> EXPORT_SYMBOL(drm_bridge_mode_set); >> >> +/** >> + * drm_bridge_format_set - setup with proposed input format and encoding for >> + * all bridges in the encoder chain >> + * @bridge: bridge control structure >> + * @input_bus_format: proposed input bus format for the bridge >> + * @input_encoding: proposed input encoding for this bridge >> + * >> + * Calls &drm_bridge_funcs.format_set op for all the bridges in the >> + * encoder chain, starting from the first bridge to the last. >> + * >> + * Note: the bridge passed should be the one closest to the encoder >> + * >> + * RETURNS: >> + * true on success, false if one of the bridge cannot handle the format > > I would return an int to propagate the failure reason upstream. It will > reach the commit tail handler in any case, so will be dropped there, but > could help debugging issues if we print it in the right place. Indeed. > >> + */ >> +bool drm_bridge_format_set(struct drm_bridge *bridge, >> + const u32 input_bus_format, >> + const u32 input_encoding) > > You don't need a const here. Noted > >> +{ >> + bool ret = true; >> + >> + if (!bridge) >> + return true; >> + >> + if (bridge->funcs->format_set) >> + ret = bridge->funcs->format_set(bridge, input_bus_format, >> + input_encoding); >> + if (!ret) >> + return ret; >> + >> + return drm_bridge_format_set(bridge->next, input_bus_format, >> + input_encoding); > > I don't think this will scale. It's not that uncommon for bridges to > change the format (most likely converting from YUV to RGB or the other > way around, or reducing the number of bits per sample) and the encoding. > We thus can't propagate it from bridge to bridge and expect that to > work. > > At the very least, the bridge should report its output bus format and > encoding, to be applied to the next bridge, but this won't allow > checking if the configuration can be applied ahead of time, resulting in > possible failures of a commit tail handler. I wonder if this wouldn't be > a good time to introduce bridge states... Ok for chaining the format_set, I thought about it when writing it. And what if a added a second call drm_bridge_format_check() to check if a future format_set chaining would work ? then we could either do the format_set, try another or fallback to a known default format setup. Would that be sufficient ? Bridge states would be interesting, but it's really out of the scope of our current needs in term of bridge changes. IMHO we can start with format_check/format_set and switch to bridges states when we have a sufficient use case needing a finer handling of states. Neil > >> +} >> +EXPORT_SYMBOL(drm_bridge_format_set); >> + >> /** >> * drm_bridge_pre_enable - prepares for enabling all >> * bridges in the encoder chain >> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h >> index d4428913a4e1..7a79e61b7825 100644 >> --- a/include/drm/drm_bridge.h >> +++ b/include/drm/drm_bridge.h >> @@ -198,6 +198,22 @@ struct drm_bridge_funcs { >> void (*mode_set)(struct drm_bridge *bridge, >> const struct drm_display_mode *mode, >> const struct drm_display_mode *adjusted_mode); >> + >> + /** >> + * @format_set: >> + * >> + * This callback should configure the bridge for the given input bus >> + * format and encoding. It is called after the @format_set callback >> + * for the preceding element in the display pipeline has been called >> + * already. If the bridge is the first element then this would be >> + * &drm_encoder_helper_funcs.format_set. The display pipe (i.e. >> + * clocks and timing signals) is off when this function is called. >> + * >> + * @returns: true in success, false is a bridge refuses the format >> + */ >> + bool (*format_set)(struct drm_bridge *bridge, >> + const u32 input_bus_format, >> + const u32 input_encoding); >> /** >> * @pre_enable: >> * >> @@ -311,6 +327,9 @@ void drm_bridge_post_disable(struct drm_bridge *bridge); >> void drm_bridge_mode_set(struct drm_bridge *bridge, >> const struct drm_display_mode *mode, >> const struct drm_display_mode *adjusted_mode); >> +bool drm_bridge_format_set(struct drm_bridge *bridge, >> + const u32 input_bus_format, >> + const u32 input_encoding); >> void drm_bridge_pre_enable(struct drm_bridge *bridge); >> void drm_bridge_enable(struct drm_bridge *bridge); >> > _______________________________________________ linux-amlogic mailing list linux-amlogic@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-amlogic