From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A54911E3DF8 for ; Mon, 1 Sep 2025 08:52:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756716749; cv=none; b=paNf+Rlroh37usG2uzdAZHVaTq2nAWcK0UpXZVlZV5R4H6fYD3BlLvrqdBOquPQ7UcVdCCcQBLSI31VX15Mg4PNHKq90E6mKsNYp6gwaMtwbw66BhNqeN+ywZEOjXxzXHaRE8xBJEBKS7gT0Ce77KtMfz1G2k4UqzfZQOOUcl8k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756716749; c=relaxed/simple; bh=eBiENUdZ7cBlGmNfmtDmzZhm3YM5dUq2S5qDOz9A49E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=n8YEjXAVGYH8Tgju27tBznjLR/Zlv0mwFm0HDVrhs6EORnwcQilJydjBrlBvI2I9eIN6uV1CT3FbmFG88cSoWkHpWOlHzflTx4CZgJH01UmAd5ezT0HOlDiQAeARB5244mUueb6MfQ68wYdgbGlYaD+VhkPW8hKCvVYIW137iU4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=BJdT2d18; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="BJdT2d18" Received: from [192.168.88.20] (91-158-153-178.elisa-laajakaista.fi [91.158.153.178]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 51236EAE; Mon, 1 Sep 2025 10:51:16 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1756716677; bh=eBiENUdZ7cBlGmNfmtDmzZhm3YM5dUq2S5qDOz9A49E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=BJdT2d18e+gP7JDDfmldCci8h7bVIQQtlhEB+ZVsyRbj8hJoQQD7XwG/PRRT8ZMuD ScaoOFDyOoNyXrfpgMM4a9SQwGuOesc60xqLb/78RhdtXAlajQ6b3Rvz72uC59FpGV MZCbu1pBOhvsYZ0HP1sAKoccmwWGHBaPpL0npeLA= Message-ID: <327d2ef2-d670-4677-ba1f-b19c2f0b4f3f@ideasonboard.com> Date: Mon, 1 Sep 2025 11:52:19 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 3/3] drm/tidss: oldi: Add atomic_check hook for oldi bridge To: Swamil Jain Cc: h-shenoy@ti.com, devarsht@ti.com, vigneshr@ti.com, praneeth@ti.com, u-kumar1@ti.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, jyri.sarha@iki.fi, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, aradhya.bhatia@linux.dev References: <20250819192113.2420396-1-s-jain1@ti.com> <20250819192113.2420396-4-s-jain1@ti.com> <837a8381-02bd-4882-bfa4-6d5c34f44119@ideasonboard.com> Content-Language: en-US From: Tomi Valkeinen Autocrypt: addr=tomi.valkeinen@ideasonboard.com; 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charset=UTF-8 Content-Transfer-Encoding: 8bit Hi, On 29/08/2025 06:50, Swamil Jain wrote: > Hi Tomi, > > On 8/27/25 14:35, Tomi Valkeinen wrote: >> Hi, >> >> On 19/08/2025 22:21, Swamil Jain wrote: >>> From: Jayesh Choudhary >>> >>> Since OLDI consumes DSS VP clock directly as serial clock, certain >>> checks cannot be performed in tidss driver which should be checked >> >> I think this is a bit misleading. The OLDI input clock doesn't come from >> DSS, so I wouldn't call it "DSS VP clock". The point here is that the >> clock from the PLL is used by both OLDI and DSS, and in the current >> architecture the OLDI driver manages the clock, so the DSS driver can't >> really do checks, it just has to accept the clock rate. All checks need >> to be done in the OLDI driver. >> >>> in OLDI driver. Add check for mode clock and set max_successful_rate >>> and max_attempted_rate field for tidss in case the VP is OLDI. >>> >>> Fixes: 7246e0929945 ("drm/tidss: Add OLDI bridge support") >>> Reviewed-by: Devarsh Thakkar >>> Signed-off-by: Jayesh Choudhary >>> Signed-off-by: Swamil Jain >>> --- >>>   drivers/gpu/drm/tidss/tidss_oldi.c | 25 +++++++++++++++++++++++++ >>>   1 file changed, 25 insertions(+) >>> >>> diff --git a/drivers/gpu/drm/tidss/tidss_oldi.c b/drivers/gpu/drm/ >>> tidss/tidss_oldi.c >>> index ef01ecc17a12..2ed2d0666ccb 100644 >>> --- a/drivers/gpu/drm/tidss/tidss_oldi.c >>> +++ b/drivers/gpu/drm/tidss/tidss_oldi.c >>> @@ -309,6 +309,30 @@ static u32 >>> *tidss_oldi_atomic_get_input_bus_fmts(struct drm_bridge *bridge, >>>       return input_fmts; >>>   } >>>   +static int tidss_oldi_atomic_check(struct drm_bridge *bridge, >>> +                   struct drm_bridge_state *bridge_state, >>> +                   struct drm_crtc_state *crtc_state, >>> +                   struct drm_connector_state *conn_state) >>> +{ >>> +    struct tidss_oldi *oldi = drm_bridge_to_tidss_oldi(bridge); >>> +    struct drm_display_mode *adjusted_mode; >>> +    unsigned long round_clock; >>> + >>> +    adjusted_mode = &crtc_state->adjusted_mode; >>> + >>> +    if (adjusted_mode->clock > oldi->tidss- >>> >max_successful_rate[oldi->parent_vp]) { >> >> You can change the above check to <=, and return 0 here early. >> >>> +        round_clock = clk_round_rate(oldi->serial, adjusted_mode- >>> >clock * 7 * 1000); >>> + >>> +        if (dispc_pclk_diff(adjusted_mode->clock * 7 * 1000, >>> round_clock) > 5) >>> +            return -EINVAL; >>> + >>> +        oldi->tidss->max_successful_rate[oldi->parent_vp] = >>> round_clock; >>> +        oldi->tidss->max_attempted_rate[oldi->parent_vp] = >>> adjusted_mode->clock * 7 * 1000; >>> +    } >> >> This is not very nice. We should have a function in tidss that we call >> here, instead of poking into these tidss's variables directly. >> >> Actually... Do we even need to use the tidss->max_* fields? The above >> code is not checking the VP clock maximum, it's actually looking at the >> serial clock maximum. Currently those two clocks are linked, though, but >> would it make more sense to have the max_* fields here, in OLDI, for >> OLDI's serial clock?We don't require tidss->max_* fields here as we >> only have single mode > for OLDI. This is added to make it consistent with check_pixel_clock() > for validating modes. > > You are right we shouldn't use tidss->* fields directly in OLDI driver. > > As Maxime suggested we only have very few modes for OLDI, can we skip > caching maximum pixel clock in case of OLDI? What would you suggest Tomi? I think it's best to at least try the trivial option discussed in this thread: just use clk_round_rate, without any code to cache or seek out the max. Tomi