[UBOOT PATCH] spi: spi-uclass: Fix reduced read speed when parallel config is enabled

[Marek Vasut]

On 2/21/25 10:57 AM, Venkatesh Yadav Abbarapu wrote:
> From: Prasad Kummari <prasad.kummari at amd.com>
> 
> When SPI_STACKED_PARALLEL is enabled, the chip selects properties
> are read from the device tree using the reg property and stored in
> the plat->cs[] array. However, the function dev_read_u32_array()
> returns zero, causing the execution to enter the else block, print
> an error message, and return. As a result, the spi-max-frequency
> property is not read from the device tree, resulting in the use
> of the default frequency SPI_DEFAULT_SPEED_HZ (100,000). This leads
> to a lower spi->speed, reducing QSPI DMA read performance.
> 
> To address this issue, an additional condition has been added to
> check the return value of reg. If it is nonzero, the function prints
> an error message and returns. Otherwise, it proceeds to read the
> spi-max-frequency property from the device tree.
> 
> Signed-off-by: Prasad Kummari <prasad.kummari at amd.com>
> Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu at amd.com>
> ---
>   drivers/spi/spi-uclass.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c
> index d6049753740..a7783b6b6dd 100644
> --- a/drivers/spi/spi-uclass.c
> +++ b/drivers/spi/spi-uclass.c
> @@ -523,8 +523,10 @@ int spi_slave_of_to_plat(struct udevice *dev, struct dm_spi_slave_plat *plat)
>   	if (ret == -EOVERFLOW || ret == -FDT_ERR_BADLAYOUT) {
>   		dev_read_u32(dev, "reg", &plat->cs[0]);
>   	} else {
> -		dev_err(dev, "has no valid 'reg' property (%d)\n", ret);
> -		return ret;
> +		if (ret) {
> +			dev_err(dev, "has no valid 'reg' property (%d)\n", ret);
> +			return ret;
> +		}
>   	}
>   #else
>   	plat->cs[0] = dev_read_u32_default(dev, "reg", -1);

Why not simply do this?

diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c
index d6049753740..4d9376dbdca 100644
--- a/drivers/spi/spi-uclass.c
+++ b/drivers/spi/spi-uclass.c
@@ -522,7 +522,7 @@ int spi_slave_of_to_plat(struct udevice *dev, struct 
dm_spi_slave_plat *plat)

         if (ret == -EOVERFLOW || ret == -FDT_ERR_BADLAYOUT) {
                 dev_read_u32(dev, "reg", &plat->cs[0]);
-       } else {
+       } else if (ret) {
                 dev_err(dev, "has no valid 'reg' property (%d)\n", ret);
                 return ret;
         }