Re: Uninitialized rx_req/tx_req (was: Re: [PATCH v2 2/3] mmc: omap_hsmmc:Skip platform_get_resource_byname() for dt case)

From: Balaji T K
Date: Thu Sep 12 2013 - 11:12:08 EST


On Thursday 12 September 2013 06:11 PM, Geert Uytterhoeven wrote:
On Tue, Mar 5, 2013 at 10:13 PM, Matt Porter <mporter@xxxxxx> wrote:
From: Santosh Shilimkar <santosh.shilimkar@xxxxxx>

MMC driver probe will abort for DT case because of failed
platform_get_resource_byname() lookup. Fix it by skipping resource
byname lookup for device tree build.

Issue is hidden because hwmod popullates the IO resources which
helps to succeed platform_get_resource_byname() and probe.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
---
drivers/mmc/host/omap_hsmmc.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index e79b12d..8ae1225 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -1896,21 +1896,23 @@ static int omap_hsmmc_probe(struct platform_device *pdev)

omap_hsmmc_conf_bus_power(host);

- res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "tx");
- if (!res) {
- dev_err(mmc_dev(host->mmc), "cannot get DMA TX channel\n");
- ret = -ENXIO;
- goto err_irq;
- }
- tx_req = res->start;
+ if (!pdev->dev.of_node) {
+ res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "tx");
+ if (!res) {
+ dev_err(mmc_dev(host->mmc), "cannot get DMA TX channel\n");
+ ret = -ENXIO;
+ goto err_irq;
+ }
+ tx_req = res->start;

- res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "rx");
- if (!res) {
- dev_err(mmc_dev(host->mmc), "cannot get DMA RX channel\n");
- ret = -ENXIO;
- goto err_irq;
+ res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "rx");
+ if (!res) {
+ dev_err(mmc_dev(host->mmc), "cannot get DMA RX channel\n");
+ ret = -ENXIO;
+ goto err_irq;
+ }
+ rx_req = res->start;
}
- rx_req = res->start;

dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);

Now this is in mainline, I get (gcc 4.1.2):

drivers/mmc/host/omap_hsmmc.c: In function ‘omap_hsmmc_probe’:
drivers/mmc/host/omap_hsmmc.c:1779: warning: ‘rx_req’ may be used
uninitialized in this function
drivers/mmc/host/omap_hsmmc.c:1779: warning: ‘tx_req’ may be used
uninitialized in this function

Indeed, rx_req and tx_req are not initialized in the DT case.

Initializing them to zero is probably not the right fix. Where are the values
supposed to come from in the DT case?

Hi,

rx_req and tx_req are not used in DT case [1].
dma_request_slave_channel is used to get dma info from mmc dt node.

__dma_request_channel is fallback case for non dt boot.

Note __dma_request_channel is called if dma info is not populated in
dts files.

static inline struct dma_chan
*__dma_request_slave_channel_compat(const dma_cap_mask_t *mask,
dma_filter_fn fn, void *fn_param,
struct device *dev, char *name)
{
struct dma_chan *chan;

chan = dma_request_slave_channel(dev, name);
if (chan)
return chan;

return __dma_request_channel(mask, fn, fn_param);
}

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds


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