[linux-sunxi] Re: [PATCH v2 2/3] mmc: sunxi: Filter out unsupported modes declared in the device tree

2019-02-06 Thread Ulf Hansson
On Tue, 5 Feb 2019 at 16:42, Chen-Yu Tsai  wrote:
>
> The MMC device tree bindings include properties used to signal various
> signalling speed modes. Until now the sunxi driver was accepting them
> without any further filtering, while the sunxi device trees were not
> actually using them.
>
> Since some of the H5 boards can not run at higher speed modes stably,
> we are resorting to declaring the higher speed modes per-board.
>
> Regardless, having boards declare modes and blindly following them,
> even without proper support in the driver, is generally a bad thing.
>
> Filter out all unsupported modes from the capabilities mask after
> the device tree properties have been parsed.
>
> Cc: 
> Signed-off-by: Chen-Yu Tsai 
>

Applied for fixes, thanks!

Kind regards
Uffe


> ---
>
> This should be backported to stable kernels in case people try to run
> new device trees (that declare newly supported modes) with old kernels.
> ---
>  drivers/mmc/host/sunxi-mmc.c | 15 +++
>  1 file changed, 15 insertions(+)
>
> diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
> index 7415af8c8ff6..70fadc976795 100644
> --- a/drivers/mmc/host/sunxi-mmc.c
> +++ b/drivers/mmc/host/sunxi-mmc.c
> @@ -1415,6 +1415,21 @@ static int sunxi_mmc_probe(struct platform_device 
> *pdev)
> if (ret)
> goto error_free_dma;
>
> +   /*
> +* If we don't support delay chains in the SoC, we can't use any
> +* of the higher speed modes. Mask them out in case the device
> +* tree specifies the properties for them, which gets added to
> +* the caps by mmc_of_parse() above.
> +*/
> +   if (!(host->cfg->clk_delays || host->use_new_timings)) {
> +   mmc->caps &= ~(MMC_CAP_3_3V_DDR | MMC_CAP_1_8V_DDR |
> +  MMC_CAP_1_2V_DDR | MMC_CAP_UHS);
> +   mmc->caps2 &= ~MMC_CAP2_HS200;
> +   }
> +
> +   /* TODO: This driver doesn't support HS400 mode yet */
> +   mmc->caps2 &= ~MMC_CAP2_HS400;
> +
> ret = sunxi_mmc_init_host(host);
> if (ret)
> goto error_free_dma;
> --
> 2.20.1
>

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[linux-sunxi] Re: [PATCH v2 2/3] mmc: sunxi: Filter out unsupported modes declared in the device tree

2019-02-06 Thread Maxime Ripard
On Tue, Feb 05, 2019 at 11:42:24PM +0800, Chen-Yu Tsai wrote:
> The MMC device tree bindings include properties used to signal various
> signalling speed modes. Until now the sunxi driver was accepting them
> without any further filtering, while the sunxi device trees were not
> actually using them.
> 
> Since some of the H5 boards can not run at higher speed modes stably,
> we are resorting to declaring the higher speed modes per-board.
> 
> Regardless, having boards declare modes and blindly following them,
> even without proper support in the driver, is generally a bad thing.
> 
> Filter out all unsupported modes from the capabilities mask after
> the device tree properties have been parsed.
> 
> Cc: 
> Signed-off-by: Chen-Yu Tsai 

Acked-by: Maxime Ripard 

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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