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SubjectRe: [PATCH] nand: ranw: qcom_nand: stop using phys_to_dma()
On Wed, 11 Jul 2018 14:26:58 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> Compile-testing this driver on x86 caused a link error:
>
> ERROR: "__phys_to_dma" [drivers/mtd/nand/raw/qcom_nandc.ko] undefined!
>
> The problem here is that the driver attempts to convert the physical
> address into the DMA controller as a dma_addr_t and calls phys_to_dma()
> to do the conversion.
>
> However, there is no generic way to convert a phys_addr_t into a dma_addr_t
> for anything other than RAM (which should use the dma-mapping API instead).
> The only correct use of phys_to_dma() instead is inside of the dma-mapping
> implementation.

Should we use dma_map_resource() to do the phys_addr_t to dma_addr_t
conversion?

>
> In all other drivers that deal with DMA FIFO addresses, we just pass the
> physical address directly and have the DMA controller deal with that
> if necessary, so let's do the same thing here.
>
> Fixes: c76b78d8ec05 ("mtd: nand: Qualcomm NAND controller driver")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/mtd/nand/raw/qcom_nandc.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
> index 994f980c6d86..f047e2819041 100644
> --- a/drivers/mtd/nand/raw/qcom_nandc.c
> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
> @@ -338,7 +338,6 @@ struct nandc_regs {
> * @dev: parent device
> * @base: MMIO base
> * @base_phys: physical base address of controller registers
> - * @base_dma: dma base address of controller registers
> * @core_clk: controller clock
> * @aon_clk: another controller clock
> *
> @@ -372,7 +371,6 @@ struct qcom_nand_controller {
>
> void __iomem *base;
> phys_addr_t base_phys;
> - dma_addr_t base_dma;
>
> struct clk *core_clk;
> struct clk *aon_clk;
> @@ -935,11 +933,11 @@ static int prep_adm_dma_desc(struct qcom_nand_controller *nandc, bool read,
> slave_conf.device_fc = flow_control;
> if (read) {
> slave_conf.src_maxburst = 16;
> - slave_conf.src_addr = nandc->base_dma + reg_off;
> + slave_conf.src_addr = (dma_addr_t)nandc->base_phys + reg_off;
> slave_conf.slave_id = nandc->data_crci;
> } else {
> slave_conf.dst_maxburst = 16;
> - slave_conf.dst_addr = nandc->base_dma + reg_off;
> + slave_conf.dst_addr = (dma_addr_t)nandc->base_phys + reg_off;
> slave_conf.slave_id = nandc->cmd_crci;
> }
>
> @@ -2963,7 +2961,6 @@ static int qcom_nandc_probe(struct platform_device *pdev)
> return PTR_ERR(nandc->base);
>
> nandc->base_phys = res->start;
> - nandc->base_dma = phys_to_dma(dev, (phys_addr_t)res->start);
>
> nandc->core_clk = devm_clk_get(dev, "core");
> if (IS_ERR(nandc->core_clk))

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