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h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=YGuK4VEzOn7RVy70U3QPgT0o0DMkyzyLKKCZ6dGONLI=; b=mctxpP9MSYD7hbyLOWSRRSBVqqsemKutamCKrA3t3shp8dvSbsfh1RbBDR4XID1Lhi uKTMDzAl5HF6D+oopiP5131xZdxXCWWS1GTCkOJyqLe2FBvHxH3m15DTIBUsHF8hX36t 4791DAYRMI772s8ef9AkGI2p0Cfaxh9LSnYXeTpz+HLf2nwvYpSD7p9+pvmL4ebd+fag RoC+TMc2Gym2GavD9dDX81ePvkr+TeLcWVx28ImhmS81my32qKwlhU79X73aoCHaYN+I YvG9sTC4ehkaqiExo/n+fcaXajDUZTj87LEkZJCFyfLgNzrjKM3BbHbV0YkyHA4XSpjG /pqg== X-Gm-Message-State: APjAAAUq4f/+z+M1BAuVtjgFEdXU9lIVz4RQFfBKs8EPs+n1lEruwQEd ZRKPH3KjoF9RcoXpZpTeNhnSbiA23hINmx7PU1krCw== X-Google-Smtp-Source: APXvYqw+NO9h3GLLVM5FCgA8092Iiix0AL1JgyjvL7yup9kh6IvbtN89iOP5WNUppRmu3zsJXlJAePWOyperb3qX848= X-Received: by 2002:a1c:f90f:: with SMTP id x15mr2463636wmh.69.1565871968857; Thu, 15 Aug 2019 05:26:08 -0700 (PDT) MIME-Version: 1.0 References: <20190703114933.u3x4ej3v7ocewvif@flea> <20190711100100.cty3s6rs3w27low6@flea> <20190720065830.zn3txpyduakywcva@flea> <20190720093202.6fn6xmhvsgawscnu@flea> <20190724090513.vqnlmya3nqkl6pmu@flea> <20190813060502.teeevudz6cjn35tl@flea> In-Reply-To: <20190813060502.teeevudz6cjn35tl@flea> From: Michael Nazzareno Trimarchi Date: Thu, 15 Aug 2019 14:25:57 +0200 Message-ID: Subject: Re: [PATCH v6 11/22] clk: sunxi-ng: a64: Add minimum rate for PLL_MIPI To: Maxime Ripard X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190815_052611_642285_712453CE X-CRM114-Status: GOOD ( 54.04 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , devicetree , David Airlie , Michael Turquette , linux-sunxi , linux-kernel , dri-devel , Chen-Yu Tsai , Rob Herring , Jagan Teki , Daniel Vetter , linux-amarula , linux-clk , linux-arm-kernel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Maxime On Tue, Aug 13, 2019 at 8:05 AM Maxime Ripard wrote: > > On Mon, Jul 29, 2019 at 08:59:04AM +0200, Michael Nazzareno Trimarchi wrote: > > Hi > > > > On Wed, Jul 24, 2019 at 11:05 AM Maxime Ripard > > wrote: > > > > > > On Mon, Jul 22, 2019 at 03:51:04PM +0530, Jagan Teki wrote: > > > > Hi Maxime, > > > > > > > > On Sat, Jul 20, 2019 at 3:02 PM Maxime Ripard wrote: > > > > > > > > > > On Sat, Jul 20, 2019 at 12:46:27PM +0530, Jagan Teki wrote: > > > > > > On Sat, Jul 20, 2019 at 12:28 PM Maxime Ripard > > > > > > wrote: > > > > > > > > > > > > > > On Thu, Jul 11, 2019 at 07:43:16PM +0200, Michael Nazzareno Trimarchi wrote: > > > > > > > > > > tcon-pixel clock is the rate that you want to achive on display side > > > > > > > > > > and if you have 4 lanes 32bit or lanes and different bit number that > > > > > > > > > > you need to have a clock that is able to put outside bits and speed > > > > > > > > > > equal to pixel-clock * bits / lanes. so If you want a pixel-clock of > > > > > > > > > > 40 mhz and you have 32bits and 4 lanes you need to have a clock of > > > > > > > > > > 40 * 32 / 4 in no-burst mode. I think that this is done but most of > > > > > > > > > > the display. > > > > > > > > > > > > > > > > > > So this is what the issue is then? > > > > > > > > > > > > > > > > > > This one does make sense, and you should just change the rate in the > > > > > > > > > call to clk_set_rate in sun4i_tcon0_mode_set_cpu. > > > > > > > > > > > > > > > > > > I'm still wondering why that hasn't been brought up in either the > > > > > > > > > discussion or the commit log before though. > > > > > > > > > > > > > > > > > Something like this? > > > > > > > > > > > > > > > > drivers/gpu/drm/sun4i/sun4i_tcon.c | 20 +++++++++++--------- > > > > > > > > drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h | 2 -- > > > > > > > > 2 files changed, 11 insertions(+), 11 deletions(-) > > > > > > > > > > > > > > > > diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c > > > > > > > > b/drivers/gpu/drm/sun4i/sun4i_tcon.c > > > > > > > > index 64c43ee6bd92..42560d5c327c 100644 > > > > > > > > --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c > > > > > > > > +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c > > > > > > > > @@ -263,10 +263,11 @@ static int sun4i_tcon_get_clk_delay(const struct > > > > > > > > drm_display_mode *mode, > > > > > > > > } > > > > > > > > > > > > > > > > static void sun4i_tcon0_mode_set_common(struct sun4i_tcon *tcon, > > > > > > > > - const struct drm_display_mode *mode) > > > > > > > > + const struct drm_display_mode *mode, > > > > > > > > + u32 tcon_mul) > > > > > > > > { > > > > > > > > /* Configure the dot clock */ > > > > > > > > - clk_set_rate(tcon->dclk, mode->crtc_clock * 1000); > > > > > > > > + clk_set_rate(tcon->dclk, mode->crtc_clock * tcon_mul * 1000); > > > > > > > > > > > > > > > > /* Set the resolution */ > > > > > > > > regmap_write(tcon->regs, SUN4I_TCON0_BASIC0_REG, > > > > > > > > @@ -335,12 +336,13 @@ static void sun4i_tcon0_mode_set_cpu(struct > > > > > > > > sun4i_tcon *tcon, > > > > > > > > u8 bpp = mipi_dsi_pixel_format_to_bpp(device->format); > > > > > > > > u8 lanes = device->lanes; > > > > > > > > u32 block_space, start_delay; > > > > > > > > - u32 tcon_div; > > > > > > > > + u32 tcon_div, tcon_mul; > > > > > > > > > > > > > > > > - tcon->dclk_min_div = SUN6I_DSI_TCON_DIV; > > > > > > > > - tcon->dclk_max_div = SUN6I_DSI_TCON_DIV; > > > > > > > > + tcon->dclk_min_div = 4; > > > > > > > > + tcon->dclk_max_div = 127; > > > > > > > > > > > > > > > > - sun4i_tcon0_mode_set_common(tcon, mode); > > > > > > > > + tcon_mul = bpp / lanes; > > > > > > > > + sun4i_tcon0_mode_set_common(tcon, mode, tcon_mul); > > > > > > > > > > > > > > > > /* Set dithering if needed */ > > > > > > > > sun4i_tcon0_mode_set_dithering(tcon, sun4i_tcon_get_connector(encoder)); > > > > > > > > @@ -366,7 +368,7 @@ static void sun4i_tcon0_mode_set_cpu(struct > > > > > > > > sun4i_tcon *tcon, > > > > > > > > */ > > > > > > > > regmap_read(tcon->regs, SUN4I_TCON0_DCLK_REG, &tcon_div); > > > > > > > > tcon_div &= GENMASK(6, 0); > > > > > > > > - block_space = mode->htotal * bpp / (tcon_div * lanes); > > > > > > > > + block_space = mode->htotal * tcon_div * tcon_mul; > > > > > > > > block_space -= mode->hdisplay + 40; > > > > > > > > > > > > > > > > regmap_write(tcon->regs, SUN4I_TCON0_CPU_TRI0_REG, > > > > > > > > @@ -408,7 +410,7 @@ static void sun4i_tcon0_mode_set_lvds(struct > > > > > > > > sun4i_tcon *tcon, > > > > > > > > > > > > > > > > tcon->dclk_min_div = 7; > > > > > > > > tcon->dclk_max_div = 7; > > > > > > > > - sun4i_tcon0_mode_set_common(tcon, mode); > > > > > > > > + sun4i_tcon0_mode_set_common(tcon, mode, 1); > > > > > > > > > > > > > > > > /* Set dithering if needed */ > > > > > > > > sun4i_tcon0_mode_set_dithering(tcon, sun4i_tcon_get_connector(encoder)); > > > > > > > > @@ -487,7 +489,7 @@ static void sun4i_tcon0_mode_set_rgb(struct > > > > > > > > sun4i_tcon *tcon, > > > > > > > > > > > > > > > > tcon->dclk_min_div = 6; > > > > > > > > tcon->dclk_max_div = 127; > > > > > > > > - sun4i_tcon0_mode_set_common(tcon, mode); > > > > > > > > + sun4i_tcon0_mode_set_common(tcon, mode, 1); > > > > > > > > > > > > > > > > /* Set dithering if needed */ > > > > > > > > sun4i_tcon0_mode_set_dithering(tcon, connector); > > > > > > > > diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h > > > > > > > > b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h > > > > > > > > index 5c3ad5be0690..a07090579f84 100644 > > > > > > > > --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h > > > > > > > > +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h > > > > > > > > @@ -13,8 +13,6 @@ > > > > > > > > #include > > > > > > > > #include > > > > > > > > > > > > > > > > -#define SUN6I_DSI_TCON_DIV 4 > > > > > > > > - > > > > > > > > struct sun6i_dsi { > > > > > > > > struct drm_connector connector; > > > > > > > > struct drm_encoder encoder; > > > > > > > > > > > > > > I had more something like this in mind: > > > > > > > http://code.bulix.org/nlp5a4-803511 > > > > > > > > > > > > Worth to look at it. was it working on your panel? meanwhile I will check it. > > > > > > > > > > I haven't tested it. > > > > > > > > > > > We have updated with below change [1], seems working on but is > > > > > > actually checking the each divider as before start with 4... till 127. > > > > > > > > > > > > This new approach, is start looking the best divider from 4.. based on > > > > > > the idea vs rounded it will ended up best divider like [2] > > > > > > > > > > But why? > > > > > > > > > > I mean, it's not like it's the first time I'm asking this... > > > > > > > > > > If the issue is what Micheal described, then the divider has nothing > > > > > to do with it. We've had that discussion over and over again. > > > > > > > > This is what Michael is mentioned in above mail "tcon-pixel clock is > > > > the rate that you want to achive on display side and if you have 4 > > > > lanes 32bit or lanes and different bit number that you need to have > > > > a clock that is able to put outside bits and speed equal to > > > > pixel-clock * bits / lanes. so If you want a pixel-clock of 40 mhz > > > > and you have 32bits and 4 lanes you need to have a clock of 40 * 32 > > > > / 4 in no-burst mode. " > > > > > > Yeah, so we need to change the clock rate. > > > > > > > He is trying to manage the bpp/lanes into dclk_mul (in last mail) > > > > and it can multiply with pixel clock which is rate argument in > > > > sun4i_dclk_round_rate. > > > > > > > > The solution I have mentioned in dclk_min, max is bpp/lanes also > > > > multiple rate in dotclock sun4i_dclk_round_rate. > > > > > > > > In both cases the overall pll_rate depends on dividers, the one that I > > > > have on this patch is based on BSP and the Michael one is more generic > > > > way so-that it can not to touch other functionalities and looping > > > > dividers to find the best one. > > > > > > > > If dclk_min/max is bpp/lanes then dotclock directly using divider 6 > > > > (assuming 24-bit and 4 lanes) and return the pll_rate and divider 6 > > > > associated. > > > > > > > > if dclk_mul is bpp/lanes, on Michael new change, the dividers start > > > > with 4 and end with 127 but the constant ideal rate which rate * > > > > bpp/lanes but the loop from sun4i_dclk_round_rate computed the divider > > > > as 6 only, ie what I'm mentioned on the above mail. > > > > > > We've been over this a couple of times already. > > > > > > The clock is generated like this: > > > > > > PLL -> TCON Module Clock -> TCON DCLK > > > > > > You want the TCON DCLK to be at the pixel clock rate * bpp / > > > lanes. Fine, that makes sense. > > > > > > Except that the patch you've sent, instead of changing the rate > > > itself, changes the ratio between the module clock and DCLK. > > > > > > And this is where the issue lies. First, from a logical viewpoint, it > > > doesn't make sense. If you want to change the clock rate, then just do > > > it. Don't hack around the multipliers trying to fall back to something > > > that works for you. > > > > > > Then, the ratio itself needs to be set to 4. This is the part that > > > we've discussed way too many times already, but in the Allwinner BSP, > > > that ratio is hardcoded to 4, and we've had panels that need it at > > > that value. > > > > > > So, what you want to do is to have: > > > > > > TCON DCLK = pixel clock * bpp / lanes > > > TCON Module Clock = DCLK * 4 > > > PLL = Module Clock * Module Clock Divider (which I believe is 1 in most cases) > > > > pll-mipi 1 1 1 178200000 > > 0 0 50000 > > tcon0 2 2 1 178200000 > > 0 0 50000 > > tcon-pixel-clock 1 1 1 29700000 > > 0 0 50000 > > Is this before or after your patches? > This is just an example of clock tree to be clear to everyone how they are connected > > This is an english problem from my side: > > tcon-pixel-clock is DCLK > > tcon0 must be tcon-pixel-clock * bpp / lanes, because the logic need to > > put a bit every cycle. > > Again, I'm not saying this is wrong, but each time I've looked at it > the BSP was using a 4 divider between the tcon module clock and the > dotclock. > We have tested on 4-5 displays. Well I don't care on bsp but I care about if it works and if other SoC has similar approach on clock calculation. > So, please prove me wrong here. > Having only 10 pages of documentation is a bit difficult. > > One solution can be: > > - set_rate_exclusive to tcon0 and calculate as display pixel clock * > > bpp / lanes > > I'm not sure what set_rate_exclusive has to do with it. I mean, it's a > good idea to use it, but it shouldn't really change anything to the > discussion. Well, this will just do a minimal change on source code and put the constrains to the tcon0 > > > - calculate the tcon-pixel-clock using all divider > > I'm not sure what you mean by that. > > > Problem is that the function that calculate tcon-pixel-clock does not > > have any constrain on the ideal value. > > It does have constraints, but you're right that it will not try to > find an exact match and bail out if it can't do it, but will find the > closest match. > We need to find the closest divider that match the pixel clock and be close to the ideal tcon0 rate. > > What you are suggesting is not correct in my opinion or I'm not > > following your suggesstion. > > Then prove me wrong. > > > What I know is that if we have a pixel-clock of dvi display of 50Mhz > > and we have 4 lanes 32bit we need a clock in the logic of 400Mhz > > (this is the ideal throughtput). > > So tcon-pixel-clock is 50mhz and tcon0 is 400Mhz. > > There's one thing to keep in mind though. The TCON dotclock in the > MIPI-DSI case isn't directly tied to the Bit Clock, it's simply an > internal clock in the pipeline to feed the FIFO of the MIPI-DSI > controller. The MIPI-DSI controller itself will generate that clock, > and only that one will have those constraints. > I have done the same thinking but because it works for us seems that somehow is used to internal logic too Michael > Maxime > > -- > Maxime Ripard, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com -- | Michael Nazzareno Trimarchi Amarula Solutions BV | | COO - Founder Cruquiuskade 47 | | +31(0)851119172 Amsterdam 1018 AM NL | | [`as] http://www.amarulasolutions.com | _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel