On Fri, May 14, 2021 at 05:53:18PM +0200, Ulrich Hecht wrote:
> The TMIO core sets a very low latency limit (100 us), but when using R-Car
> SDHI hosts with SD cards, I have observed typical latencies of around 20-30
> ms. This prevents runtime PM from working properly, and the devices remain
> on continuously.
> 
> This patch sets the default latency limit to 100 ms to avoid that.
> 
> Signed-off-by: Ulrich Hecht <uli+renesas@fpond.eu>

Adding Shimoda-san to CC.

Shimoda-san: can you kindly run your SDHI tests with this patch applied?
That would be very kind, thank you!

> ---
>  drivers/mmc/host/renesas_sdhi_core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
> index 635bf31a6735..4f41616cc6bb 100644
> --- a/drivers/mmc/host/renesas_sdhi_core.c
> +++ b/drivers/mmc/host/renesas_sdhi_core.c
> @@ -32,6 +32,7 @@
>  #include <linux/pinctrl/pinctrl-state.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_domain.h>
> +#include <linux/pm_qos.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/reset.h>
>  #include <linux/sh_dma.h>
> @@ -1147,6 +1148,9 @@ int renesas_sdhi_probe(struct platform_device *pdev,
>  		host->ops.hs400_complete = renesas_sdhi_hs400_complete;
>  	}
>  
> +	/* keep tmio_mmc_host_probe() from setting latency limit too low */
> +	dev_pm_qos_expose_latency_limit(&pdev->dev, 100000);
> +
>  	ret = tmio_mmc_host_probe(host);
>  	if (ret < 0)
>  		goto edisclk;
> -- 
> 2.20.1
>