Subject: [PATCH] mmc: omap_hsmmc: Add support for Erratum 2.1.1.128 in device tree boot

From: [email-masked] (Balaji T K)
Date: Tue, 4 Feb 2014 18:14:08 +0530

On Tuesday 21 January 2014 04:59 AM, Nishanth Menon wrote:
> When device is booted using devicetree, platforms impacted by
> Erratum 2.1.1.128 is not detected easily in the mmc driver. This erratum
> indicates that the module cannot do multi-block transfers.
>
> Handle this by providing a boolean flag to indicate to driver that it is
> working on a hardware with mentioned limitation.
>
> Signed-off-by: Nishanth Menon <[email-masked]>
> ---
>
> This explains the logs I see:
> OMAP3430 LDP (ES2.2):
> 	uImage only boot:  http://slexy.org/raw/s2YrbMAi7c
> 	uImage+dtb concatenated boot: http://slexy.org/raw/s20qVg17T0
>
> With the following flag set, device is now able to consistently boot with
> device tree supported uImage+dtb concat boot.
>
>   .../devicetree/bindings/mmc/ti-omap-hsmmc.txt      |    2 ++
>   drivers/mmc/host/omap_hsmmc.c                      |    3 +++
>   2 files changed, 5 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
> index 8c8908a..ab36f8b 100644
> --- a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
> +++ b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
> @@ -26,6 +26,8 @@ specifier is required.
>   dma-names: List of DMA request names. These strings correspond
>   1:1 with the DMA specifiers listed in dmas. The string naming is
>   to be "rx" and "tx" for RX and TX DMA requests, respectively.
> +ti,erratum-2.1.1.128: boolean, for OMAP3430/OMAP35xx platforms with broken
> +multiblock reads

Rather than ti,errata.. specific property, something like
caps no/disable multiblock read is more readable in my opinion, Otherwise

Acked-by: Balaji T K <[email-masked]>

>
>   Examples:
>
> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> index 014bfe5..f2d5940 100644
> --- a/drivers/mmc/host/omap_hsmmc.c
> +++ b/drivers/mmc/host/omap_hsmmc.c
> @@ -1730,6 +1730,9 @@ static struct omap_mmc_platform_data *of_get_hsmmc_pdata(struct device *dev)
>   	if (of_find_property(np, "ti,dual-volt", NULL))
>   		pdata->controller_flags |= OMAP_HSMMC_SUPPORTS_DUAL_VOLT;
>
> +	if (of_find_property(np, "ti,erratum-2.1.1.128", NULL))
> +		pdata->controller_flags |= OMAP_HSMMC_BROKEN_MULTIBLOCK_READ;
> +
>   	/* This driver only supports 1 slot */
>   	pdata->nr_slots = 1;
>   	pdata->slots[0].switch_pin = cd_gpio;
>