Re: [PATCH 6/6] ARM: da850: adjust memory settings for tilcdc

[Peter Ujfalusi]

On 09/29/16 19:31, Bartosz Golaszewski wrote:
> Default memory settings of da850 do not meet the throughput/latency
> requirements of tilcdc. This results in the image displayed being
> incorrect and the following warning being displayed by the LCDC
> drm driver:
> 
>   tilcdc da8xx_lcdc.0: tilcdc_crtc_irq(0x00000020): FIFO underfow
> 
> Reconfigure the LCDC priority to the highest. This is a workaround
> for the da850-lcdk board which has the LCD controller enabled in
> the device tree, but a long-term, system-wide fix is needed for
> all davinci boards.
> 
> This patch has been modified for mainline linux. It comes from a
> downstream TI release for da850[1].
> 
> Original author: Vishwanathrao Badarkhe, Manish <manishv.b@xxxxxx>
> 
> [1] http://arago-project.org/git/projects/linux-davinci.git?p=projects/linux-davinci.git;a=commitdiff;h=b9bd39a34cc02c3ba2fc15539a2f0bc2b68d25da;hp=6f6c795faa6366a4ebc1037a0235edba6018a991
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> ---
>  arch/arm/mach-davinci/da8xx-dt.c           | 43 ++++++++++++++++++++++++++++++
>  arch/arm/mach-davinci/include/mach/da8xx.h |  4 +++
>  2 files changed, 47 insertions(+)
> 
> diff --git a/arch/arm/mach-davinci/da8xx-dt.c b/arch/arm/mach-davinci/da8xx-dt.c
> index f8ecc02..9d29670 100644
> --- a/arch/arm/mach-davinci/da8xx-dt.c
> +++ b/arch/arm/mach-davinci/da8xx-dt.c
> @@ -44,9 +44,52 @@ static struct of_dev_auxdata da850_auxdata_lookup[] __initdata = {
>  
>  #ifdef CONFIG_ARCH_DAVINCI_DA850
>  
> +/*
> + * Adjust the default memory settings to cope with the LCDC
> + *
> + * REVISIT: This issue occurs on other davinci boards as well. Find
> + * a proper system-wide fix.
> + */
> +static void da850_lcdc_adjust_memory_bandwidth(void)
> +{
> +	void __iomem *cfg_mstpri1_base;
> +	void __iomem *cfg_mstpri2_base;
> +	void __iomem *emifb;
> +	u32 val;
> +
> +	/*
> +	 * Default master priorities in reg 0 are all lower by default than LCD
> +	 * which is set below to 0. Hence don't need to change here.
> +	 */
> +
> +	/* set EDMA30TC0 and TC1 to lower than LCDC (4 < 0) */
> +	cfg_mstpri1_base = DA8XX_SYSCFG0_VIRT(DA8XX_MSTPRI1_REG);
> +	val = __raw_readl(cfg_mstpri1_base);
> +	val &= 0xFFFF00FF;
> +	val |= 4 << 8;             /* 0-high, 7-low priority*/
> +	val |= 4 << 12;            /* 0-high, 7-low priority*/
> +	__raw_writel(val, cfg_mstpri1_base);
> +
> +	/*
> +	 * Reconfigure the LCDC priority to the highest to ensure that
> +	 * the throughput/latency requirements for the LCDC are met.
> +	 */
> +	cfg_mstpri2_base = DA8XX_SYSCFG0_VIRT(DA8XX_MSTPRI2_REG);
> +
> +	val = __raw_readl(cfg_mstpri2_base);
> +	val &= 0x0fffffff;
> +	__raw_writel(val, cfg_mstpri2_base);
> +
> +	/* set BPRIO */
> +	emifb = ioremap(DA8XX_DDR_CTL_BASE, SZ_4K);
> +	__raw_writel(0x20, emifb + DA8XX_PBBPR_REG);
> +	iounmap(emifb);

Is this safe to do for all da850 boards (to change PR_OLD_COUNT from 0xff to
0x20)? Most probably it is, but this setting has nothing to do with LCDC.

The whole priority configuration has nothing to do with the LCDC, it is a
system level priority.

Now you have lowered the eDMA3_0-TPTC0/1 priority. Audio is serviced by
eDMA3_0-TPTC1. So are we going to see issues in audio if LCDC is taking the
highest priority?

> +}
> +
>  static void __init da850_init_machine(void)
>  {
>  	of_platform_default_populate(NULL, da850_auxdata_lookup, NULL);
> +	da850_lcdc_adjust_memory_bandwidth();
>  }
>  
>  static const char *const da850_boards_compat[] __initconst = {
> diff --git a/arch/arm/mach-davinci/include/mach/da8xx.h b/arch/arm/mach-davinci/include/mach/da8xx.h
> index f9f9713..5549eff 100644
> --- a/arch/arm/mach-davinci/include/mach/da8xx.h
> +++ b/arch/arm/mach-davinci/include/mach/da8xx.h
> @@ -56,6 +56,8 @@ extern unsigned int da850_max_speed;
>  #define DA8XX_SYSCFG0_VIRT(x)	(da8xx_syscfg0_base + (x))
>  #define DA8XX_JTAG_ID_REG	0x18
>  #define DA8XX_HOST1CFG_REG	0x44
> +#define DA8XX_MSTPRI1_REG	0x114
> +#define DA8XX_MSTPRI2_REG	0x118
>  #define DA8XX_CHIPSIG_REG	0x174
>  #define DA8XX_CFGCHIP0_REG	0x17c
>  #define DA8XX_CFGCHIP1_REG	0x180
> @@ -79,6 +81,8 @@ extern unsigned int da850_max_speed;
>  #define DA8XX_AEMIF_CTL_BASE	0x68000000
>  #define DA8XX_SHARED_RAM_BASE	0x80000000
>  #define DA8XX_ARM_RAM_BASE	0xffff0000
> +#define DA8XX_DDR_CTL_BASE	0xB0000000
> +#define DA8XX_PBBPR_REG		0x00000020
>  
>  void da830_init(void);
>  void da850_init(void);
> 


-- 
Péter