linux-kernel - Re: [PATCH] drm/meson: viu: fix setting the OSD burst length in VIU_OSD1_FIFO_CTRL

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Message-ID: <bf7e6eb5-4655-e958-819b-9d14effe745e@baylibre.com>
Date:   Tue, 28 Apr 2020 10:38:00 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        jmasson@...libre.com, linux-amlogic@...ts.infradead.org
Cc:     dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/meson: viu: fix setting the OSD burst length in
 VIU_OSD1_FIFO_CTRL_STAT

Hi,
On 25/04/2020 22:39, Martin Blumenstingl wrote:
> The burst length is configured in VIU_OSD1_FIFO_CTRL_STAT[31] and
> VIU_OSD1_FIFO_CTRL_STAT[11:10]. The public S905D3 datasheet describes
> this as:
> - 0x0 = up to 24 per burst
> - 0x1 = up to 32 per burst
> - 0x2 = up to 48 per burst
> - 0x3 = up to 64 per burst
> - 0x4 = up to 96 per burst
> - 0x5 = up to 128 per burst
> 
> The lower two bits map to VIU_OSD1_FIFO_CTRL_STAT[11:10] while the upper
> bit maps to VIU_OSD1_FIFO_CTRL_STAT[31].
> 
> Replace meson_viu_osd_burst_length_reg() with pre-defined macros which
> set these values. meson_viu_osd_burst_length_reg() always returned 0
> (for the two used values: 32 and 64 at least) and thus incorrectly set
> the burst size to 24.
> 
> Fixes: 147ae1cbaa1842 ("drm: meson: viu: use proper macros instead of magic constants")
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> ---
>  drivers/gpu/drm/meson/meson_registers.h |  6 ++++++
>  drivers/gpu/drm/meson/meson_viu.c       | 11 ++---------
>  2 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/meson/meson_registers.h b/drivers/gpu/drm/meson/meson_registers.h
> index 8ea00546cd4e..049c4bfe2a3a 100644
> --- a/drivers/gpu/drm/meson/meson_registers.h
> +++ b/drivers/gpu/drm/meson/meson_registers.h
> @@ -261,6 +261,12 @@
>  #define VIU_OSD_FIFO_DEPTH_VAL(val)      ((val & 0x7f) << 12)
>  #define VIU_OSD_WORDS_PER_BURST(words)   (((words & 0x4) >> 1) << 22)
>  #define VIU_OSD_FIFO_LIMITS(size)        ((size & 0xf) << 24)
> +#define VIU_OSD_BURST_LENGTH_24          (0x0 << 31 | 0x0 << 10)
> +#define VIU_OSD_BURST_LENGTH_32          (0x0 << 31 | 0x1 << 10)
> +#define VIU_OSD_BURST_LENGTH_48          (0x0 << 31 | 0x2 << 10)
> +#define VIU_OSD_BURST_LENGTH_64          (0x0 << 31 | 0x3 << 10)
> +#define VIU_OSD_BURST_LENGTH_96          (0x1 << 31 | 0x0 << 10)
> +#define VIU_OSD_BURST_LENGTH_128         (0x1 << 31 | 0x1 << 10)
>  
>  #define VD1_IF0_GEN_REG 0x1a50
>  #define VD1_IF0_CANVAS0 0x1a51
> diff --git a/drivers/gpu/drm/meson/meson_viu.c b/drivers/gpu/drm/meson/meson_viu.c
> index 304f8ff1339c..aede0c67a57f 100644
> --- a/drivers/gpu/drm/meson/meson_viu.c
> +++ b/drivers/gpu/drm/meson/meson_viu.c
> @@ -411,13 +411,6 @@ void meson_viu_gxm_disable_osd1_afbc(struct meson_drm *priv)
>  			    priv->io_base + _REG(VIU_MISC_CTRL1));
>  }
>  
> -static inline uint32_t meson_viu_osd_burst_length_reg(uint32_t length)
> -{
> -	uint32_t val = (((length & 0x80) % 24) / 12);
> -
> -	return (((val & 0x3) << 10) | (((val & 0x4) >> 2) << 31));
> -}
> -
>  void meson_viu_init(struct meson_drm *priv)
>  {
>  	uint32_t reg;
> @@ -444,9 +437,9 @@ void meson_viu_init(struct meson_drm *priv)
>  		VIU_OSD_FIFO_LIMITS(2);      /* fifo_lim: 2*16=32 */
>  
>  	if (meson_vpu_is_compatible(priv, VPU_COMPATIBLE_G12A))
> -		reg |= meson_viu_osd_burst_length_reg(32);
> +		reg |= VIU_OSD_BURST_LENGTH_32;
>  	else
> -		reg |= meson_viu_osd_burst_length_reg(64);
> +		reg |= VIU_OSD_BURST_LENGTH_64;
>  
>  	writel_relaxed(reg, priv->io_base + _REG(VIU_OSD1_FIFO_CTRL_STAT));
>  	writel_relaxed(reg, priv->io_base + _REG(VIU_OSD2_FIFO_CTRL_STAT));
> 

Thanks,
Will run some tests !

Neil