linux-kernel - [PATCH v3] staging: fbtft: Disable DMA support if DMA is not available

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Message-Id: <1429861455-32645-1-git-send-email-geert@linux-m68k.org>
Date:	Fri, 24 Apr 2015 09:44:15 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Noralf Trønnes <noralf@...nnes.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH v3] staging: fbtft: Disable DMA support if DMA is not available

If NO_DMA=y:

    drivers/built-in.o: In function `fbtft_framebuffer_alloc':
    (.text+0xb53cae): undefined reference to `dmam_alloc_coherent'

As DMA support is already optional, make it depend on HAS_DMA.

Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
v3:
  - Use an #ifdef instead of relying on compiler optimization,

v2:
  - Explain better how it works,
  - Keep the "= false" to avoid breakage (seen not only with gcc 4.1.2,
    but also with 4.6.3 and 4.9.0).
---
 drivers/staging/fbtft/fbtft-core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index 53b748be27124793..ce645213a5393b8b 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -47,9 +47,11 @@ static unsigned long debug;
 module_param(debug, ulong, 0);
 MODULE_PARM_DESC(debug, "override device debug level");
 
+#ifdef CONFIG_HAS_DMA
 static bool dma = true;
 module_param(dma, bool, 0);
 MODULE_PARM_DESC(dma, "Use DMA buffer");
+#endif
 
 
 void fbtft_dbg_hex(const struct device *dev, int groupsize,
@@ -856,10 +858,13 @@ struct fb_info *fbtft_framebuffer_alloc(struct fbtft_display *display,
 #endif
 
 	if (txbuflen > 0) {
+#ifdef CONFIG_HAS_DMA
 		if (dma) {
 			dev->coherent_dma_mask = ~0;
 			txbuf = dmam_alloc_coherent(dev, txbuflen, &par->txbuf.dma, GFP_DMA);
-		} else {
+		} else
+#endif
+		{
 			txbuf = devm_kzalloc(par->info->device, txbuflen, GFP_KERNEL);
 		}
 		if (!txbuf)
-- 
1.9.1

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